It's the national anthem, celebrating Old Glory's "broad stripes and bright stars" as it's sung at baseball games, presidential rallies and high school graduations. "The Star-Spangled Banner" is one of the nation's grandest symbols.

Yet historians fear that the origin of the song, first penned as a poem by Francis Scott Key, is easily forgotten or, worse, unknown -- even here in Washington, a region drenched in history. Key penned the poem in honor of U.S. efforts in the War of 1812, the British-American war that brought the country new confidence and patriotism.

So historians have teamed up with politicians to commemorate the war, parts of which were fought up and down the Chesapeake Bay. Congress is considering legislation that would designate as a national historic trail a 290-mile path winding through Virginia, Maryland and the District to link the war's battle sites.

The Star-Spangled Banner Trail would begin in Southern Maryland near St. Leonard Creek and loop up to such sites as Alexandria, Washington, Bladensburg and Baltimore. It was in Baltimore that Key witnessed British ships firing on Fort McHenry, where the U.S. flag survived the "rockets' red glare" and "bombs bursting in air."

Local historian Ralph Eshelman, who has been a leading voice in support of the trail designation, said he is perplexed that many people don't know the origin of the national anthem.

"If this is arguably America's greatest icon, and people don't really understand how it came to be, what greater way than a national trail to get people to better understand that?" Eshelman said.

Sen. Paul S. Sarbanes (D-Md.) and Rep. Benjamin L. Cardin (D-Md.) introduced legislation in the spring for the trail's designation. Their bills are winding their way through Congress.

The project has been a long time in the making. The National Park Service spent several years developing a comprehensive plan for the trail and expects it to be completed in time for the war's 200th anniversary in 2012.

"The route pretty much exists," said William Sharp, the Park Service's project manager. "It's a combination of land and water routes. The land routes, for the most part, follow existing roads."

The national designation would require interpretative materials such as trail markers explaining the battles and history of the war, Sharp said. There are 16 historic trails in the country, including the Lewis & Clark Trail, the Pony Express Trail, the Oregon Trail and the Selma to Montgomery Trail.

The Star-Spangled Banner Trail also would commemorate broader political and social trends of the time, such as the changing role of the federal government, the brewing controversy over slavery and the country's struggle for a national identity, said Eshelman, who lives in Calvert County, Md.

"So what, in fact, is the significance of the war?" he asked. "It gave Americans for the first time confidence that it actually felt that this country would survive. We had just defeated the world's most powerful naval force, and so Americans now had new confidence. They had new patriotism."