Like many in Miami, a writer for the Cities blog at The Atlantic noticed signs of an increase in commuting by bike. He turned to Census data to test his impression and found startling growth in the Northwest -- and a surprising decline in Miami. Here's the article: Is Bicycle Commuting Really Catching On?
I'm not sure how reliable these charts are. The problem is the underlying data. The baseline numbers come from the 2000 census and the comparisons from the American Community Survey, taken during 2005-2009. In the latter study, however, a commuter trip is attributed to bicycling only if that's the dominant mode used. Someone who bikes to work two days a week and takes the bus three days will show as a bus rider, not as 2/5 of a bike commuter. And someone who bikes to the train is not counted as a cyclist unless the daily bike ride is longer than the train ride. The numbers are further explored by the League of American Bicyclists.