Columbia subject headings:
Automobile ownership--United States--Statistics--Databases.
Commuting--United States--Statistics--Databases.
Traffic surveys--United States--Databases.
Transportation, Automotive--United States--Statistics--Databases.
Harvard subject headings:
Automobile ownership--United States--Statistics--Databases.
Commuting--United States--Statistics--Databases.
Traffic surveys--United States--Databases.
Transportation, Automotive--United States--Statistics--Databases.
Princeton subject headings: