Maryland and Virginia’s transportation officials met earlier this month to explore the possibility of building another Potomac River crossing, reviving a discussion of the idea of an outer Beltway loop that has been booted about for decades.

The aim remains the same: siphon traffic away from the Capital Beltway so that travelers from outside the region who want to bypass Washington and its suburbs could motor up I-95 in Virginia, cross the Potomac over a new link upriver from the American Legion Bridge in Cabin John,.and connect with Route 270 in Maryland.

But a key problem also remains: namely, where exactly?

Virginia Transportation Secretary Sean Connaughton disclosed the new push for a second crossing while talking with reporters Wednesday following a luncheon hosted by the Greater Reston Chamber of Commerce to discuss Dulles rail. Such a link could eliminate 15 percent of rush-hour traffic on the Beltway.

“We’ve started to engage in discussions with the state of Maryland,” he said. “It may not have support with all the special interests.”

A spokesman for Maryland’s Department of Transportation said Thursday that Maryland and Virginia transportation officials met March 9 to follow up a general discussion between Gov. Martin O’Malley and Gov. Robert F. McDonnell.

“These discussions are very preliminary,” said Jack Cahalan, a spokesman for the Maryland Department of Transportation. “We’d like to keep the dialogue going. . . This has been on the radar screen for many decades.”

In the past, Maryland has refused to consider a link that would land in Montgomery County’s agricultural preserve. It has long insisted that a bridge north of the Beltway should land no farther south than Point of Rocks in Frederick County, where a bridge already carries Route 15 across the Potomac.

Virginians have traditionally viewed that location as too far west, arguing for a link between western Montgomery County and Loudoun County that could serve as a “techway” between Interstate 270 in suburban Maryland and high-tech offices near Dulles International Airport in Northern Virginia.