More commuters are turning to bicycles today for national Bike-to-Work Day as gas prices continue to reach record highs.

"It's going to be the biggest yet," says Bill Nesper of the League of American Bicyclists, which promotes May as national Bike Month. "Our phone is ringing off the hook. We're getting lots of calls from around the country. People are doing this because of gas prices."

No one tracks exactly how many Americans participate annually, but Nesper says more than 84 cities are expected to take part this year with rallies and other events.

He says more than 6,500 people are expected to ride to work today in the Washington metropolitan region, which includes Maryland and Northern Virginia.

Seattle expects 20,000 riders to participate, up from 19,000 last year, says Rick Sheridan, a spokesman for the city's Department of Transportation.