I don't think there's any problem with citing an official Census Bureau report. Certainly they are the definitive source for statistics on the U.S. population.

I don't think there's any problem with citing an official Census Bureau report. Certainly they are the definitive source for statistics on the U.S. population. And I imagine the numbers in the report give a correct overall impression of commute times. However, I suspect the conclusions in the report as to the accuracy of the data are a bit overblown.