Most cyclists cross the Potomac River on either the 14th Street Bridge or Key Bridge. Even more people might use these bridges if there were more ways to get to them by bike.
On the average July weekday this year, each carried around 2,000 riders: it was 2,028 for the 14th Street Bridge, and 1,950 for the Key Bridge. The Roosevelt Bridge saw an average of 474 cyclists per July weekday.
An average of 3,013 cyclists used all three bridges on weekdays during the first seven months of 2015. This equals an average of 1,352 cyclists on the 14th Street Bridge, 1,338 on the Key Bridge and 324 on the Roosevelt Bridge.
This data comes from Arlington County.
Cyclists can also cross the Potomac River on the Chain Bridge, Memorial Bridge and Woodrow Wilson Bridge, but there is little data available on exact use.
Cycling peaks during the summer
Bike commuting across the Potomac is most common during the relatively pleasant late spring and summer months. An average of 4,453 cyclists crossed the river on the three bridges during weekdays in July.
People used the Potomac crossings least during the winter. An average of 973 cyclists used the bridges on weekdays in January — about a fifth of the number that used them in July.
Interestingly, the annual Cherry Blossom Festival in March and April does not result in a spike in weekday cycling traffic across any the Potomac. This could be because bike commuters prefer to avoid the crowds around the Tidal Basin where they access the 14th Street Bridge in DC. It could also be that many have yet to resume cycling after a winter hiatus.
Better connections to the 14th Street and Key Bridges would serve a lot of cyclists
The 14th Street Bridge connects to the Mount Vernon Trail in Virginia, where cyclists can easily continue on to Crystal City, Ronald Reagan Washington National airport and Old Town Alexandria. Ideas for better connections include ones to the Pentagon and Long Bridge Park, potentially as part of the Long Bridge replacement.
In the District, the bridge drops cyclists just south of the Jefferson Memorial. From there, they have to ride on the sidewalk or with traffic across the Mall to reach the city’s protected bikeway network. Ideas to improve the connection include extending the protected bikeway on 15th Street NW to Constitution Avenue, adding signage to the route and widening the off-street path.
The Key Bridge is well connected to the Custis Trail, Mount Vernon Trail and Rosslyn in Virginia. But on the District side cyclists either have to ride with traffic on congested M Street or descend two sets of stairs to reach the Capital Crescent Trail and K Street. The Georgetown Business Improvement District’s Georgetown 2028 includes some improvements to the District side, as well as a new crossing to Roosevelt Island.