Commuters who travel to work via bicycle put a dent in petroleum consumption and air pollution, and likely have a leg up on not becoming part of the obesity epidemic. Davis, CA, residents are at the head of the pack of the 375 largest US cities surveyed, with 22.1% of the city's residents commuting by bike, according to US Census Bureau statistics compiled by the League of American Bicyclists.
- "2010 Bike Commuting Data Released,"  Sept. 23, 2011.
- More details on each available city, 2009. 
Other leading cities in 2010 were Boulder, CO (9.9%), Eugene, OR (8.3%), Berkeley, CA (8.0%), and Cambridge, MA (6.8%). At the other end of the spectrum were many cities at 0.1%.
- 2010 Bike Commuters, All Places  (includes data on total population, number of workers, and breakouts by gender).
Among the 70 largest cities, the highest percentages were in Portland, OR (6.0%), Seattle, WA (3.6%), San Francisco, CA (3.5%), Minneapolis, MN (3.5%), and Washington, D.C. (3.1%). At the bottom of the list, all with 0.1%, were Memphis, TN, El Paso, TX, Omaha, NE, Fort Worth, TX, and Bakersfield, CA.
- 2000 to 2010 Bike Commuters, Largest 70  (overall, the trend is up, but still averages just 1% for these 70 cities, and half that for the US).
It's apparent that climate alone isn't driving these numbers, since higher percentages occur in a number of cold or wet climates, and low percentages occur in mild climates.
Instead, it's likely that political and sociocultural influences are playing major roles. These statistics provide an indirect opportunity to explore which factors are playing dominant roles, and to address issues such as perceptions regarding petroleum use, climate change, pollution, health, social status, personal responsibility, and the so-called "nanny state." There also may be communities that don't fit with the trends apparent with the leaders and laggards, offering another avenue of investigation.
Of course, you can also cover this as just a basic bicycling story.
Incidentally, the statistics above relate only to regular commuting. They don't account for sporadic commuting, or recreational use. A way to address one slice of those uses is to investigate bike sharing programs that may exist in the communities you cover. For more on that topic, see the TipSheet of Feb. 4, 2009.