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This report is available for downloading from the MTC web site. Text files are in Microsoft Word and "Rich Text Format." The spreadsheets are available in Microsoft Excel workbook formats. The files are in a "zipped" archive format and requires PKUNZIP, WINZIP, etc., to extract the files. The file to download is: aopaper.zip

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Table of Contents

Section
1. Introduction
2. Changes in Bay Area Demographic Characteristics
3. Changes in Household Auto Ownership
3.1 Historical Patterns
3.2 Projected Patterns
3.3 The Big Picture: Vehicle Ownership between 1930 and 2010
4. Changes in Bay Area Vehicle Ownership
4.1 Historical Changes in Vehicle Ownership - 1930-1990
4.2 Recent Changes in Vehicle Ownership- 1977-1996
4.3 Changes in Motorcycle Ownership - 1930-1996
5. Changes in Bay Area Driver Population
6. Conclusions
7. References
Related WWW Resources

List of Tables
Table 1 Number of Households, Bay Area Counties - 1930-2010
Table 2 Population in Households, Bay Area Counties - 1930-2010
Table 3 Household Size, Bay Area Counties - 1930-2010
Table 4 Total Population, Bay Area Counties - 1930-2010
Table 5 Percent Change in Total Population, Bay Area Counties - 1930-2010
Table 6 Estimate of Total Population - 1978-1997
Table 7 Share of Bay Area Total Population by County - 1978-1997
Table 8 Distribution of Households by Vehicle Availability - 1960-1990
Table 9 Distribution of Households by Vehicle Availability - 1990, 2000, 2010
Table 10 Growth in Bay Area Auto Ownership, 1930-2010
Table 11 Registered Automobiles - Estimated Fee Paid Vehicles - 1930-1990
Table 12 Registered Commercial/Trucks - Estimated Fee Paid Vehicles - 1930-1990
Table 13 Registered Personal Vehicle - Estimated Fee Paid Vehicles - 1930-1990
Table 14 Registered Autos, Trucks, Vans - Estimated Fee Paid Vehicles - 1930-1990
Table 15 Average Autos Registered per Household - 1930-1990
Table 16 Average Autos Registered per Person - 1930-1990
Table 17 Average Total Vehicles Registered per Household - 1930-1990
Table 18 Average Total Vehicles Registered per Person - 1930-1990
Table 19 Average Personal Vehicles Registered per Household - 1930-1990
Table 20 Average Personal Vehicles Registered per Person - 1930-1990
Table 21 Registered Automobiles - Estimated Fee Paid Vehicles - 1977-1996
Table 22 Registered Commercial/Trucks - Estimated Fee Paid Vehicles - 1977-1996
Table 23 Registered Personal Vehicle - Estimated Fee Paid Vehicles - 1977-1996
Table 24 Registered Autos, Trucks, Vans - Estimated Fee Paid Vehicles - 1977-1996
Table 25 Autos Available per Person (Autos/1000 Persons - 1977-1996
Table 26 Motorcycle Estimated Fee Paid Registrations, Bay Area Counties - 1930-1996
Table 27 Drivers Licenses Outstanding, 1978-1996
Table 28 Average Autos Registered per Licensed Driver, 1978-1996
Table 29 Share of Population with Drivers Licenses, 1978-1996
Table 30 Density of Auto Ownership by Bay Area County, 1996

Table A-1 Growth in Auto Ownership by Bay Area Counties, 1930-2010
Table A-2 California Statewide Estimated Fee Paid Vehicle Registrations
Table A-3 International Auto and Vehicle Ownership Comparison - 1995
Table A-4 US Metro Area Comparison, 1990, Ranked by Total Population
Table A-5 US Metro Area Comparison, 1990, Ranked by Vehicles per 1000 Persons

List of Figures
Figure 1 Total Population in the San Francisco Bay Area, 1930-2010
Figure 2 Share of Households by Autos Available, San Francisco Bay Area, 1960-1990
Figure 3 Total Population, Households and Vehicle Ownership, San Francisco Bay Area 1930-2010
Figure 4 Vehicle Availability per Capita, San Francisco Bay Area 1930-2010
Figure 5 Vehicles Available per 1000 Persons, San Francisco Bay Area Counties, January 1, 1997
Figure 6 Change in Bay Area Motorcycle Registrations - 1977 - 1996
Figure 7 Autos Registered per Licensed Driver, 1996

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I. Introduction

This report is a compilation of statistics on the demographic and vehicle ownership characteristics of San Francisco Bay Area residents. Data is from various sources, including the State Department of Motor Vehicles (DMV), the State Department of Finance (DOF), the U.S. Bureau of the Census, the Association of Bay Area Governments (ABAG), and the Metropolitan Transportation Commission (MTC). Historical (1930-1997) statistics as well as future year forecasts (2000, 2010) are provided.

The purpose of this report is to provide transportation planners, policy-makers and the public a sense of the change occurring in the Bay Area in terms of increasing levels of motorization and the impact on mobility and accessibility patterns. Statistical trends provide an excellent perspective on past history and future possibilities for the Bay Area.

The bulk of this report are the detailed tables and charts. The text is intended to forewarn the data user about data limitations, as well as to provide some context and interpretation for the information contained in these tables.

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II. Changes in Bay Area Demographic Characteristics

Historical demographic characteristics are available from the decennial censuses conducted by the U.S. Bureau of the Census. Demographic data from the 1930 through 1990 Censuses are used to complement the vehicle ownership data available from 1930 to the present from the State of California Department of Motor Vehicles (DMV). Census data is summarized, by Bay Area county, in Tables 1 through 5. These first five tables include data on households, population in households, average household size, total population and percent change in total population.

Annual estimates of total population by city and county are prepared by the California State Department of Finance, Demographic Research Unit (http://www.dof.ca.gov). Estimates of Bay Area county total population for the years 1978 through 1997 are included in Tables 6 and 7. According to the state demographer:

"population estimates are made using data from a variety of sources, including birth and death counts provided by the Department of Health Services, driver's license address change data from the Department of Motor Vehicles, employment data from the Employment Development Department, school enrollment data, and federal income tax data."(1)

State DOF population estimates are also benchmarked, or adjusted, to be consistent with the federal decennial census population count.

The decennial census count of households and population in households, 1930 to 1990, is included in Tables 1 and 2. Also shown in these tables are ABAG's projected households and household population for the years 2000 and 2010, based on Projections '96 (2). Data on average household size, 1930 to 2010, is provided in Table 3.

An important note is that the count of households and household population was first collected by the Census Bureau in 1940. The 1930 values, as shown, are for the number of families and persons in families. Households include persons residing alone (one-person households). Families are two-or-more persons residing together, related by marriage, blood or adoption. Families, by definition, exclude one-person households. Persons residing together, not related by marriage, blood or adoption ("roommates") are considered households but not families.

The 1970s showed the largest gain in the number of Bay Area households over the 1930 to 2010 time span. The number of households increased from 1.55 million households in 1970 to 1.97 million households by 1980, an increase of 418 thousand additional households, or a 27 percent growth. At a county level, the largest numeric gain in households was in Santa Clara County in the 1960s, which gained 138 thousand new households in the 1960s (and 136 thousand new households in the 1970s).

In terms of population in households, the Bay Area largest growth decade was the 1960s, when the household population increased from 3.51 million (1960) to 4.49 million (1970) a gain a 979 thousand new persons. Santa Clara County shows the largest population gain by county, adding 418 thousand new residents in the 1960s. San Francisco County is the only Bay Area county showing a decline in household population in any period, declining from 711 thousand persons in 1960, to 689 thousand persons in 1970, and bottoming out at 654 thousand persons in 1980. During this same 1960 to 1980 time period, the average household size in San Francisco declined from 2.44 (1960) to 2.34 (1970) to 2.19 (1980) persons per household.

Average household size in the San Francisco Bay Area has steadily declined from a high of 3.19 persons per household in 1940 to a low of 2.57 persons per household in 1980. The 1990 Census showed a reverse in this trend with regional average household size increasing to 2.61 persons per household. ABAG is projecting a continued trend in increasing household size, forecasting an average household size of 2.71 persons per household by the year 2010.

Total population includes persons residing in household and persons residing in group quarters. Group quarters includes institutional group quarters (correctional institutions, nursing homes, psychiatric hospitals and juvenile institutions) and noninstitutional group quarters (college dormitories, military quarters, emergency shelters, visible in street locations). Group quarters population comprises about 2.6 percent of the Bay Area population in 1990.

The decade of 1960s sustained the largest increase in Bay Area total population, adding nearly one million new residents between 1960 and 1970. Bay Area total population increased from 3.64 million residents in 1960 to 4.63 million residents in 1970. This was a fairly sustained period of urban growth in the Bay Area, which gained 947 thousand new residents in the 1940s and 958 thousand new residents in the 1950s.

Other than the pre-war 1930s, the 1970s showed the smallest growth in Bay Area population, adding just 549 thousand new residents between 1970 and 1980. The 1980s reversed this slow growth trend, gaining 844 thousand new residents between 1980 and 1990.

ABAG's growth forecasts show the Bay Area increasing by 907 thousand new residents in the 1990s, and adding 608 thousand new residents in the first decade of the twenty-first century (2000-2010). The San Francisco Bay Area is expected to breach the 7.0 million population mark by around the year 2001.

At a county level, Contra Costa County population nearly tripled between 1940 and 1950 (100 to 299 thousand residents). Santa Clara County population more than doubled between 1950 and 1960 (290 to 642 thousand residents). Only San Francisco, which was at a post-war-time high of 775 thousand persons in 1950, showing a decline in total population, bottoming out at 679 thousand residents in the year 1980.

The State DOF annual estimates of Bay Area county population, 1978 to 1997, is shown in Table 6. County share of Bay Area total population is shown in Table 7. These annual estimates of total population are merged with the DMV vehicle registration statistics to provide a picture of recent change in per capita vehicle ownership trends. Annual estimates of total households and household population are not normally produced by the State Department of Finance, so only total population figures are provided here. Data as shown represents total population as of January 1 of the year in question.

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III. Changes in Household Auto Ownership

This section analyzes household auto ownership patterns in the San Francisco Bay Area. Data is extracted from the U.S. decennial census, California State Department of Motor Vehicles (DMV) records, and MTC/ABAG forecasts.

3.1. Historical Patterns

Data on the number of vehicles available to each household was first asked in the U.S. Decennial Census of 1960, and has been asked in all censuses since 1960. The exact question in the 1990 Census reads: "How many automobiles, vans, and trucks of one-ton capacity or less are kept at home for use by members of your household?" Valid answers range from "none" to "7 or more."

Strictly speaking, the data from the decennial census relates to vehicles available to household members, not automobile ownership, per se. Comparisons of census-based vehicles available to DMV data shows that the census data is higher than automobiles registered, yet is less than total vehicles registered. This is probably because a good share of commercially-plated vehicles are "personal use" vehicles that are kept at home for use by household members.

The number of households by vehicle availability level, by Bay Area county of residence, is shown in Table 8. This table shows a general trend, at the regional level, of decreasing shares of zero-vehicle and one-vehicle households, and increasing shares of multi-vehicle households (see also Figure 2). The Bay Area regional share of zero-vehicle households declined from 19.7 percent of households in 1960 to 10.5 percent of Bay Area households by the year 1990. The absolute number of zero-vehicle households declined from a high of 246 thousand households in 1970 to 237 thousand households in 1990. At the opposite end of the vehicle availability spectrum, the share of households with three-or-more vehicles has increased from 3.3 percent of households in 1960 to 20.5 percent of households by 1990. The number of Bay Area households with three-or-more vehicles increased from just 38 thousand households in 1960 to 460 thousand households in 1990.

At a county level, San Francisco has always shown the lowest vehicle availability levels. The share of zero-vehicle households residing in San Francisco declined from 42.1 percent of households in 1960 to 30.7 percent of San Francisco households by 1990. The total number of zero-vehicle households has also declined in San Francisco between 1960 (123 thousand) and 1990 (94 thousand households). This compares to the other Bay Area counties which have all shown slight to moderate increases in absolute numbers of zero-vehicle households between 1960 and 1990.

Alameda County traditionally has the second lowest vehicle availability level in the Bay Area. The share of Alameda households with zero vehicles declined from 18.6 percent of households in 1960 to 12.2 percent of households in 1990. The absolute number of zero-vehicle households in Alameda increased from 55 thousand households in 1960, to 61 thousand households in both 1970 and 1980, then declined to 59 thousand households in the year 1990. As with all other Bay Area counties, Alameda has shown a steady if not spectacular increase in the share of multi-vehicle households.

Santa Clara County has the highest auto ownership level in the Bay Area, with two out of every three households currently having two-or-more vehicles. Santa Clara has the highest 1990 share of households with three-or-more vehicles (25.8 percent), and the second lowest 1990 share of households with zero vehicles (5.3 percent). Only Marin County has a lower zero vehicle household share, at 5.1 percent of Marin households.

3.2. Projected Patterns

The Metropolitan Transportation Commission produces long range travel forecasts in support of regional transportation planning activities. One element of MTC's forecasts is the projection of the number of households by vehicle availability level, that is, how many households are projected to have zero, one, or two-or-more vehicles in the household. MTC's auto ownership models are estimated on household survey data collected by MTC; and are calibrated against 1980 decennial census counts of household by vehicle availability level. MTC household vehicle availability forecasts, by Bay Area county, for the years 1990, 2000 and 2010, are summarized in Table 9. These forecasts are based on ABAG's Projections '94 household and household income forecasts, and MTC's travel behavior models. (These auto ownership models have since been recalibrated to 1990 census data, but future year forecasts are not yet available based on these new MTC models. This explains the differences in 1990 values between Tables 8 and 9.)

MTC is forecasting an absolute decline in the number of zero-vehicle households in the Bay Area, and an absolute increase in single-vehicle and multi-vehicle households. ABAG forecasts an overall 24.3 percent growth in the number of regional households between 1990 and 2010. MTC predicts a 14.5 percent decrease in the number of zero-vehicle households and a 43.3 percent increase in the number of multi-vehicle households, 1990 to 2010. In terms of vehicles per household, MTC predicts an increase from 1.76 vehicles per household in 1990 to 2.03 vehicles per household by the year 2010. In terms of the total number of household vehicles, MTC predicts a 43.6 percent increase over this twenty year period, from 3.95 million vehicles in 1990 to 5.68 million vehicles by the year 2010.

The reasons behind this faster growth in household vehicles as compared to the number of Bay Area households are:

1. Increased household income. ABAG is projecting a 35.1 percent increase in real household income between 1990 and 2010, from $29,500 in 1990 to $39,900 in 2010 (1979 constant dollars);
2. Increased suburbanization. Auto ownership is determined, in part, by the relative accessibility of activities by automobile and by transit. Areas with high frequency, high quality transit service (e.g., San Francisco, Oakland) have lower vehicle ownership levels. Area with lower quality transit service have higher vehicle ownership levels. ABAG is projecting only 28 thousand new households in San Francisco County as opposed to 479 thousand new households in the other Bay Area counties; and,
3. Increased average household size. ABAG is projecting that the average household size in the Bay Area will increase from 2.61 persons per household in 1990 to 2.71 persons per household by the year 2010. Larger households are associated with more vehicles available per household.

At a county level, the MTC forecasts show an across-the-board increase in the share of multi-vehicle households, and an across-the-board decrease in the share of zero-vehicle households. In terms of vehicles per household, San Francisco County is projected to have the lowest rate, at 1.30 vehicles/household; Santa Clara, the highest, at 2.26 vehicles per household by the year 2010. Solano County is projected to have the second highest vehicle ownership rate, at 2.20 vehicles per household in 2010. Alameda County is projected to have the second lowest vehicle ownership rate, at 1.93 vehicles per household.

3.3. The Big Picture: Vehicle Ownership between 1930 and 2010

Estimates of the number of household vehicles available, total households, vehicles per household, total population and vehicles per capita, 1930 to 2010, are shown in Table 10 and Figure 3. This 80 year profile reflects a composite picture of the Bay Area from various data sources, including the state DMV (vehicle data for 1930-1950); the U.S. Census Bureau (population and households for 1930-1990, vehicle availability data for 1960-1990); the Association of Bay Area Governments (population and households for 2000 and 2010); and MTC (vehicle data for 2000 and 2010).

These regional values show a steady increase in the levels of Bay Area motorization, expressed both in terms of vehicles per household and vehicles per capita. The Bay Area in 1930 had an average of one vehicle for every family. By the year 2010 this is expected to average just over two vehicles for every household. The Bay Area in 1930 had 29 vehicles for every 100 residents. In 1990, this had grown to 66 vehicles for every 100 residents, and by the year 2010 MTC is expecting 75 vehicles for every 100 residents (see Figure 4).

The vehicle ownership "saturation" level is an interesting concept that has been debated in the transportation planning community over the years. The thought is that there is a "ceiling" on the number of vehicles registered per licensed driver or vehicles registered per person of driving age. The common sense value of 1.0 vehicles per driver makes intuitive sense (you can only drive one vehicle at a time!), though the proliferation of secondary use vehicles, exceeding the total number of drivers in the household, may not be an uncommon phenomena. In terms of vehicles per capita, it does not appear that a saturation level can be precisely defined.

Comparison of the Bay Area to California and the United States is included in the following table:

Area	Household Vehicles	Total Households	Total Population	Vehicles per Household	Vehicles per Capita
Bay Area	3,950,200	2,246,200	6,023,600	1.76	.66
California	18,448,200	10,399,700	29,760,000	1.77	.62
United States	153,701,100	91,993,600	248,709,800	1.67	.62

This shows that the Bay Area has a slightly higher vehicle ownership level (vehicles per capita) than either the State of California or the United States, and basically the same vehicles per household level as the State of California.

County-level data for the 1930 to 2010 period is included in Appendix Table A-1. The data, again, is based on decennial census, California State DMV, ABAG and MTC statistics.

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IV. Changes in Bay Area Vehicle Ownership

This section analyzes vehicle registration data available from the California State Department of Motor Vehicles from 1930 to 1997. Tables 11 through 26 and Figure 5 are discussed in this section. The tables related to auto or vehicle registrations per person or per household are based on DMV registration statistics and either decennial census or California State Department of Finance (DOF) population counts or estimates (see Section 1).

The State Department of Motor Vehicles is responsible for licensing automobiles, trucks, trailers and motorcycles in the State of California. This is a challenging job given the large number of vehicles purchased, sold, scrapped, imported to and exported from the state on an ongoing basis. DMV is also in charge of licensing drivers. (For more information on the mission and goals of the DMV, visit their web site at: http://www.dmv.ca.gov/).

Before 1977, DMV provided annual estimates of vehicles registered for each of the 58 California counties. Since 1977, DMV estimates the total number of "fee paid" vehicles, by county, as of December 31 of the year in question. "Fee exempt" vehicles (typically public agency vehicles) are not estimated at the county level. Fee exempt vehicles represent less than 2 percent of vehicles registered in the State of California (377 thousand out of 24.1 million vehicles in California as of 12/31/96). At the end of each calendar year, DMV analysts review current as well as outstanding registrations (registrations not paid) to develop estimates of the vehicle fleet in California. These year end estimates are updated to consider recent months registration data.

4.1 Historical Changes in Vehicle Ownership - 1930-1990

Historical vehicle registration data by Bay Area County, 1930 to 1990, are shown in Tables 11 through 14. Data includes tables on registered automobiles (Table 11), registered commercial vehicles (trucks)(Table 12), registered "personal use vehicles" (Table 13), and total registered vehicles (automobiles, trucks, vans; excluding motorcycles)(Table 14). MTC staff linearly interpolated data for 4/1/80 and 4/1/90 based on estimates for 12/31/79, 12/31/80, 12/31/89 and 12/31/90.

The MTC estimate of "personal use vehicles" is based on truck surveys (1977 federal Truck Inventory and Use Survey, or TIUS) which indicate that 66.6 percent of all commercial trucks registered are used for personal activities. This "personal use vehicles" is basically a compromise between the DMV automobiles and DMV total vehicles estimate to come up with a category that is most similar to the U.S. decennial census and MTC household survey estimates of household vehicle availability. The following table compares the decennial census estimate of vehicles available to the household with DMV automobile, personal use and total vehicle estimates for the same census year:

Year	Household Vehicles, Decennial Census Estimate	Automobiles Registered, California State DMV	"Personal Use" Vehicles, California State DMV	Total Vehicles Registered, California State DMV
1960	1,314,670	1,488,058	1,620,557	1,686,808
1970	2,077,935	2,266,856	2,503,103	2,621,230
1980	3,317,203	2,866,910	3,281,813	3,489,267
1990	3,950,226	3,641,919	4,253,029	4,558,594

Unfortunately, estimates of decennial census household vehicles do not reconcile with DMV registration statistics. Census estimates are closest for the 1980 year, but are substantially less than DMV-based estimates for 1960, 1970 and 1990. These discrepancies may be due to several factors, including incorrect assumptions of vehicles per multi-vehicle household for the 1960 and 1970 censuses; DMV record-keeping practices of the pre-1977 era; household's cognition of the census question with respect to commercially-plated or company vehicles operated by household members; and other unknown reasons.

Decennial census data for the years 1930 to 1990 are merged with DMV registration data in Tables 15 through 20. Automobiles registered per household and per capita, by Bay Area county, are shown in Tables 15 and 16. These two tables are derived from the automobile registration data (Table 11) and the total household (Table 1) and total population (Table 4). These data show that automobiles registered per capita increased from 28 autos per 100 residents in 1930 to 60 autos per 100 residents by 1990. San Francisco County has historically and currently the lowest automobile ownership rates. High DMV registrations in San Mateo County show San Mateo (not Santa Clara) to have the highest automobile ownership rates, per household and per capita.

Total vehicles per household and per capita, by Bay Area county, 1930 to 1990, are summarized in Tables 17 and 18. These rates are exaggerated due to commercial and company vehicles included in the analysis, and do not reflect household auto ownership trends, but overall ratios of the entire vehicle fleet in the region relative to the Bay Area population. San Francisco County has the lowest overall ratio of total vehicles to total population in 1990, with 406,600 total vehicles and 724,000 total population (56 vehicles registered per 100 residents). San Mateo County has the highest overall ratio in 1990, with 583 thousand vehicles registered in a county with a 1990 population of 650 thousand (90 vehicles registered per 100 residents).

Personal use vehicles per household and per capita, by Bay Area county, 1930 to 1990, are shown in Tables 19 and 20. Again, discrepancies between the census and DMV vehicles tend to suggest higher DMV vehicles per household (1.89 in 1990) than the U.S. decennial census and MTC surveys suggest (1.76 in 1990 for the region).

4.2 Recent Changes in Vehicle Ownership - 1977-1996

Year-by-year change in DMV automobile, commercial vehicle and total vehicle registrations in the Bay Area are shown in Tables 21 through 25. Data is for December 31 of the year in question. Tables are provided on registered automobiles (Table 21), registered commercial vehicles / trucks (Table 22), estimate of personal use vehicles (Table 23), and total automobiles / trucks / vans estimated fee paid vehicles (Table 24).

Automobile registrations in the Bay Area have steadily increased since 1977, with two exceptions: a decline in auto registrations between 1980 and 1981; and a decline between 1993 and 1994. About 63 thousand additional cars per year are added to the Bay Area fleet, or about a 1.9 percent per year annual growth rate. Santa Clara County crested the one million automobile registration mark in late 1995. Given the trends, the Bay Area should exceed four million automobiles before the end of 1997.

Commercial vehicle registrations have shown an inconsistent trend in the Bay Area between 1977 and 1996 (Table 22). Registrations showed a consistently increasing trend between 1977 and 1990, reaching a high point of 961 thousand commercial vehicles in 1990. Commercial registrations then showed a steady decrease, falling to 875 thousand commercial vehicles by the end of 1994. Registrations have since increased, with current, end of 1996 commercial registrations at just over 900 thousand commercially-plated vehicles in the Bay Area.

Total vehicle registrations in the Bay Area are at an all-time high at over 4.8 million registered "fees paid" vehicles (Table 24). This represents an average gain of 81 thousand additional total registered vehicles added per year in the nine-county region, or a 2.0 percent growth per year.

Auto registrations per capita, expressed in autos per 1000 persons, is shown in Table 25 and graphed in Figure 5. Auto registrations per capita are calculated based on the December 31 auto data from Table 21 and the January 1 total population data included in Table 6. The merging of different datasets from the state DMV and the state DOF (population estimates) sometimes yields either interesting or suspicious trends. As shown in Table 25, autos registered per capita increased fairly steadily between 1977 and 1988, from 538 autos per 1000 persons to 612 autos per 1000 persons. This auto per capita trend has flattened our since 1988, settling down to 597 autos registered per 1000 persons by the end of 1996. The current ranking of Bay Area counties in terms of auto registrations per capita is charted in Figure 5. San Mateo County currently has the largest number of autos per capita, at 742 per 1000 persons. San Francisco County the lowest, at 437 autos per capita. Interestingly, Solano County, at 529 autos per 1000 residents, has a lower overall auto ownership rate than Alameda County, at 562 autos per 1000 residents.

4.3 Changes in Motorcycle Ownership - 1930-1996

State Department of Motor Vehicle data on motorcycle registrations are included in Table 26 and Figure 6. Bay Area motorcycle registrations reached their peak level in 1985, with nearly 153 thousand motorcycles. Total motorcycle registrations have declined to just over 126 thousand motorcycles by the end of 1996.

On a per capita basis, motorcycles per capita, in 1996, range from 17 motorcycles per 1000 residents in Alameda County to 24 motorcycles per 1000 residents in Marin County. Other counties with higher than regional average motorcycle registrations include Sonoma County (23 per 1000 persons), Napa (22 per 1000 persons), and San Francisco (22 per 1000 persons). During the peak registration year of 1985, the region had 27 motorcycles registered per 1000 residents, ranging from 22 motorcycles per 1000 residents in San Francisco County to 33 motorcycles per 1000 residents in Napa County.

V. Changes in Bay Area Driver Population

The California State Department of Motor Vehicles is responsible for licensing of drivers in the state. This section discusses changes in the Bay Area population of licensed drivers between 1978 and 1996. Data is included in Tables 27 through 29 and Figure 7. The number of drivers licenses outstanding as of December 31, by Bay Area county, is shown in Table 27. Table 28 includes the average number of autos registered per licensed driver. Autos registered per licensed driver for the end of year 1996, by county, is graphed in Figure 7. And, finally, Table 29 shows the share of total population with drivers license, by county, 1978 to 1996.

The number of Bay Area licensed drivers has increased steadily since 1978 (Table 27). On an average year, 55 thousand additional drivers are licensed in the Bay Area. This amounts to a 1.4 percent per year increase in the driver population.

As of the end of 1996 there were just over 4.4 million licensed drivers, to go along with the 3.9 million registered automobiles in the nine-county Bay Area. The average number of autos registered per licensed driver has increased from 0.82 autos/driver in 1978 to 0.89 autos/driver by the close of 1996 (Table 28).

This particular "mobility indicator" ranges from a low of 0.69 autos/driver in San Francisco (1996) to a high of 1.07 autos per licensed driver in San Mateo County (see Figure 7). Low values would indicate a high degree of competition between drivers for available autos; high values indicate availability of autos for all licensed members of a household.

These are exceptionally (if not unbelievably) high auto availability rates for San Mateo, where the DMV estimate of automobiles registered has exceeded the DMV estimate of San Mateo County licensed drivers since 1988! The other seven Bay Area counties cluster around the 0.85 to 0.92 autos per licensed driver range.

The share of persons holding drivers license is derived by dividing state DMV licensed drivers estimates by state DOF total population estimates. Unfortunately this does not measure the more meaningful measure of the share of driving age population (age 16 and over) with drivers license, but the ratio of total drivers to total population, where population includes children not eligible to drive.

It is unclear whether the low share of Solano County population that is registered to drive (62.0 percent) is due to a large share of children or to a large share of adults that are not licensed to drive. ABAG estimates that 24.7 percent of the Solano County population is less than 15 years of age, so an adjusted "share of population age 15+ with drivers license" is more like 82.3 percent (232.7 thousand drivers, 282.6 thousand persons age 15+ in Solano County as of 12/31/96).

At the other extreme, ABAG estimates that just 16.4 percent of Marin County population is less than 15 years of age. An adjusted "share of population age 15+ with drivers license" for Marin County as of 12/31/96 is 92.1 percent (186.4 thousand drivers and 202.4 thousand persons age 15+ in Marin). Overall, the data in Table 29 makes sense, such that the number of registered drivers does not appear to exceed the number of persons of driving age!

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VI. Conclusions

Data on auto ownership density, in terms of automobiles registered per total acre or residential acre, by county, is shown in Table 30.

Three appendix tables are also included in this technical summary. Table A.1 shows county-level changes in auto ownership and population between 1930 and 2010. Appendix Table A.2 shows growth in the state of California vehicle registrations between 1930 and 1996. And, lastly, appendix Table A.3 compares Bay Area and California auto and vehicles registrations to other countries with total car ownership levels exceeding 1.0 million passenger cars.

This last table on international comparisons shows that the San Francisco Bay Area has the highest auto ownership rate of all regions or countries with more than 1.0 million passenger cars (592 autos per 1000 persons). In terms of total vehicle ownership rate, the Bay Area (at 729 vehicles per 1000 persons) is slightly less than the United States (at 750 vehicles per 1000 persons). If California was a country, it would rank seventh in the world in terms of the number of passenger cars owned. If the San Francisco Bay Area was a country, it would rank 21st in the world in terms of car ownership, before South Africa and after Taiwan.

Authors Note: Two additional tables are included in the online version of this paper: Table A.4 Comparative U.S. Metropolitan Vehicle Availability, 1990, Ranked by Total Population Table A.5 Comparative U.S. Metropolitan Vehicle Availability, 1990, Ranked by Vehicles Available per 1000 Persons

Auto Ownership and Land Use

Auto ownership density can be represented in terms of autos (or vehicles) registered divided by units of land use. Land use is most often expressed in terms of acres, square miles, or square kilometers; and in terms of gross area or net area (e.g., residential acres). For the Bay Area as a whole, auto ownership density is about 0.9 autos per total acre; 8.3 autos per residential acre; 217.8 autos per total square kilometers; or 2063 autos per residential square kilometer. Densities per acre can be converted into densities per square mile by multiplying the values in Table 30 by 640 (640 acres in a square mile).

By county, auto ownership densities are lowest in the North Bay counties and highest in San Francisco. The auto ownership density in San Francisco (2812 autos/sq.km.) is six times as high as the next densest county (San Mateo, at 450 autos/sq.km.) Alameda and Santa Clara rank third and fourth highest in terms of highest auto ownership density.

Contra Costa ranks fifth in terms of gross auto ownership density, but trails Solano County in net auto ownership density due to lower residential densities in Contra Costa County compared to Solano County. Sonoma County has the lowest residential density in the Bay Area, and the lowest density measured in autos registered per residential acre (4.0 autos/residential acre).

Conclusions and Next Steps

The purpose of this report is to provide Bay Area planners, policy-makers, the media and the general public with a sense of the changes in the Bay Area in terms of auto ownership, vehicle availability, and the people who drive these vehicles. Both historical and projected data are included in this analysis. This work is essentially "data fusion" where we meld together statistics from various, often conflicting, sources: the California State Departments of Motor Vehicle (DMV) and the California State Department of Finance (DOF); the U.S. Bureau of the Census; and projections developed by the Association of Bay Area Governments (ABAG) and the Metropolitan Transportation Commission (MTC).

The next steps in this analysis will be to update the demographic and auto ownership forecasts based on ABAG's upcoming Projections '98 demographic forecast. MTC will prepare auto ownership forecasts based on ABAG's new demographic projection series as part of the update of the Regional Transportation Plan. The horizon years for this analysis will include: 2000, 2010 and the year 2020.

Depending on user needs, this report will be updated to incorporate new data from the DMV and DOF, as well as the new ABAG forecasts.

Unfortunately, DMV data is not reported at finer than county-level scale, so sub-county trends in vehicle and driver registration cannot be reported. On the other hand, Census statistics and ABAG forecasts can be reported at finer-grained levels, for example, at MTC's 34 superdistrict level. MTC's zone-level auto ownership forecasts have been and will continue to be made available over the WWW.

This report, as well as selected tables, will be included on the MTC world wide web page at:
/

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References

1. California Demographics Demographic Research Unit, California Department of Finance, Sacramento, California, Spring 1997, p. 9.

2. Projections '96 Association of Bay Area Governments, Oakland, California, 1995.

3. World Road Statistics: 1991-1995 Edition 1996. International Road Federation, Geneva, Switzerland, 1996.

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Related World Wide Web Resources

Organization	WWW address
Metropolitan Transportation Commission	/
Association of Bay Area Governments	http://www.abag.ca.gov/
California Department of Motor Vehicles	http://www.dmv.ca.gov/
California Department of Finance, Demographic Research Unit	http://www.dof.ca.gov/html/Demograp/druhpar.htm
US Bureau of the Census	http://www.census.gov/
US Bureau of Transportation Statistics	http://www.bts.gov/
International Road Federation	http://web.eunet.ch/irf/

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