Q. Where can I find data and statistics on the number of vehicles per household in the US?
National Household Travel Survey (NHTS)
Summary of Travel Trends: vehicle availability and usage statistics for the years 1969, 1977, 1983, 1990, 1995, 2001, and 2009
See Section 6.0 Vehicle Use and Availability
US Census Bureau
American Community Survey (ACS): detailed information about the American people and workforce