In this photo, racers approach the top of the Seven Mile Bridge near Marathon, Fla., during the Seven Mile Bridge Run. The event, across the longest of 43 bridges that help comprise the Overseas Highway in the Florida Keys, attracts more than 1,500 competitors. (AP Photo/Florida Keys News Bureau, Andy Newman)

In this photo, racers approach the top of the Seven Mile Bridge near Marathon, Fla., during the Seven Mile Bridge Run. The event, across the longest of 43 bridges that help comprise the Overseas Highway in the Florida Keys, attracts more than 1,500 competitors. (AP Photo/Florida Keys News Bureau, Andy Newman)