Results from the US Department of Transportation's 2009 National Household Travel Survey indicate that transit's work trip market share in the United States was only 3.7 percent in 2009. This is a full one quarter less than the 5.0 percent reported by the Bureau of the Census American Community Survey for 2009. Further, the NHTS data does not include people who work at home. If the work at home share of employment from the American Community Survey is assumed, the transit work trip market share would be 3.5 percent.
Much of the difference is due the differing questions asked in the two surveys. The American Community Survey asks how people "usually" got to work last week, while the National Household Travel Survey (NTHS) data is based upon actual diaries of travel kept by respondents. The NHTS reports that among people who respond that transit is their "usual mode" of travel to work, transit is used only 68 percent of the time. In contrast, the daily trip diaries report that commuters who drive alone are a larger share of the market than those who indicate driving alone as their usual mode of travel. People who report their usual mode as "car pool" actually use a car pool to get to work only 55 percent of the time, an even lower rate relative to "usual" mode than transit.
The daily trip diaries from the NHTS also a large difference in travel times between automobile commuters (including car pools) and transit. The average automobile commute time was 22.9 minutes, while the average transit commute time was more than double, at 53.0 minutes.