Good news for mathematicians who love watching throngs of cyclists stream by: Portland, Oregon just became the first U.S. city to install a bicycle counter!
You'll find the digital "bicycling barometer" on the AM inbound side of the Hawthorne Bridge. It was made possible by the non-profit group Cycle Oregon, which purchased the machine with a $20,000 grant. Lots of extra details are over at Bike Portland, including an in-depth look at how the system works.
Seattle is reportedly just about to install one as well. Which city or location in the U.S. should be next? Where would you put one?
