The eternal back-and-forth between home and work...The most environmentally-friendly ways to commute to work are to walk and bike, followed by mass-transit, then probably car-pooling and other similar options, and then by individual vehicle. Some cities do better than others on each of those options, though, and so those who live in bike heaven should be careful not to blame those who live in places where you can't go anywhere without crossing a 10-lane freeway for not biking more...
Speaking of biking, the U.S. Census Bureau has been compiling statistics on how many commuters use bikes. Using this data, Bloomberg has created a visualization of the top 25 bike-to-work cities in the US, which you can see above, and in higher resolution here.
The first thing that stands out is that the West coast is crushing it! And the non-coastal Western states are also doing very well. The Eastern half of the country is doing well too, but not nearly as much. This is despite big progress in many cities, such as New York City, probably because even though the absolute number of cyclists has gone up a lot, the relative percentage is still small compared to mass-transit and other options.
Special kudos to the top 5!
And if you're going to be riding every day to commute, here are a few tips on how to set up your bike like a pro.