U.S. urbanized areas with the most transit travel based on unlinked passenger trips 2011

According to the U.S. Census Bureau (Census 2000), an urbanized area is defined as a densely settled area that has a census population of at least 50,000. An urbanized area generally consists of a geographic core of block groups or blocks that have a population density of at least 1,000 people per square mile, and adjacent block groups and blocks with at least 500 people per square mile.
Unlinked passenger trips are defined as the number of passengers who board public transportation vehicles. Passengers are counted each time they board vehicles no matter how many vehicles they use to travel from their origin to their destination.
Summed from data reported by individual transit agencies in the Federal Transit Administration 2009 National Transit Database. Total amounts reported by each agency are included in the urbanized area in which that agency is headquartered regardless of the number of urbanized areas in which the agency operates transit service.