Notes: Totals include unreported characteristics. Bus includes local transit bus, commuter bus, school bus, charter/tour bus, and city-to-city bus. Rail includes subway/elevated rail, street car/trolley, and Amtrak/intercity train. Totals may not sum to 100 due to rounding. Other/Unknown includes: ferry, hotel/airport shuttle, light electric vehicle, limousine, passenger line/ferry, sailboat/motorboat/yacht, ship/cruise, special transit, taxicab, other, and unknown.
Source: U.S. Department of Transportation, Federal Highway Administration, National Household Travel Survey, available at http://nhts.ornl.gov/ accessed October 2012.