Traffic flows over the American Legion Bridge along the Beltway in this file photo. (Chip Somodevilla/Getty Images)

Leaders in the region’s two largest counties on Tuesday called for a renewed push to relieve traffic congestion for weary commuters who use the aging American Legion Bridge.

In a joint letter to the governors and transportation secretaries of Maryland and Virginia, members of the Montgomery County Council and the Fairfax County Board of Supervisors say the two states must “come together and focus on making improvements to address the severe congestion problems at the American Legion Bridge.”

As hundreds of thousands of commuters can attest, the 53-year-old bridge is a major chokepoint in the region. With nearly 300,000 vehicles crossing it daily, the bridge is the single-most-used Potomac River crossing in the Washington region.

“As you certainly appreciate, the American Legion Bridge is a vital transportation and economic link for not only Fairfax and Montgomery, but for Maryland and Virginia and, in some ways, the entire East Coast,” the officials state in the letter. “And today, it is a choke point that has serious negative consequences for our economies, our environment and our quality of life.”

Officials said that speeds during afternoon rush hours on the bridge typically slow to 34.9 mph on the outer loop and 22.5 mph on the inner loop. The posted speed limit is 55.

The letter noted that the two counties have made efforts to find a solution for easing congestion on the bridge. In 2012, Montgomery and Fairfax requested that transportation officials in both states add two high occupancy toll (HOT) lanes to the Capital Beltway from the Interstate 270 west spur to Virginia. But their request went nowhere, according to Montgomery County Council member Roger Berliner (D-Bethesda), who chairs that panel’s transportation committee.

“Nothing ever came of it,” Berliner said. But with this letter, “We’re basically saying ‘Hello? Guess what, traffic is getting worse.’ ”

Sharon Bulova, chairwoman of the Fairfax County Board of Supervisors, noted that Virginia’s experience with public/private partnerships might offer on strategy for moving the effort forward.

“The time has come for us to really put the focus on the American Legion Bridge,” she said.

Regional leaders acknowledge that Virginia has taken steps to ease congestion, including a series of improvements along Interstate 495, but say it will take cooperation between both states to truly make a difference.

“[U]ntil we collectively address the bridge itself, cars will remain stuck in gridlock,” the leaders wrote.

In July, a study by the Virginia Department of Transportation that examined 11 Potomac River crossings noted that drivers on the American Legion Bridge suffer the worst congestion. The authors of the study, which was presented to the Commonwealth Transportation Board, recommended the state work with Maryland to find a solution.

Virginia Transportation Secretary Aubrey Layne called the requests in the letter “a step in the right direction.”

“This is consistent with where we’d like to see some action,” he said, noting that he had spoken with Maryland Transportation Secretary Pete K. Rahn.

Getting buy-in from Maryland’s top leaders will be critical to any solution. However, Maryland Gov. Larry Hogan (R) has shown little interest in a HOT lane project tied to the Legion Bridge. It was not part of the highway spending plan the governor outlined in June. Rahn could not be reached for comment.

In their letter, Fairfax and Montgomery officials also address discussions related to building a second Potomac crossing, saying they think commuters would be better served by improvements to the existing Legion Bridge. Citing Virginia’s “Morning Commuter Traffic Crossing American Legion Bridge” study, they noted that a “significant percentage of Bridge commuters are headed for destinations along, or within, the Beltway corridor.”

The bottom line, according to Berliner, is that the bridge is a bottleneck that neither state can continue to ignore.

“They need to make it a priority now, “ Berliner said. “Nothing happens until you make it a priority. Once you’ve made it a priority, I can’t imagine any federal officials would say no.”

Antonio Olivo contributed to this report.