Martinsburg, W.Va. ? Brian Tolstyka stood at the edge of a giant American flag spread across several tables in the Veterans Affairs hospital gym. Wearing a leather vest with a flag patch and a hat with a flag pin, Tolstyka was about to stitch his place in history.

Gently clasping a threaded needle between thumb and forefinger, Tolstyka, 43, slipped it into the fabric of a red stripe. The 300 people in the West Virginia gym clapped. The Gulf War veteran felt a lump in his throat.

The 30-foot flag flew from a half-destroyed building across from ground zero in New York in those dark days after Sept. 11 — its stripes torn and tattered by debris from the fallen World Trade Center. In 2008, it was mended by 58 tornado survivors in Kansas with remnants of flags from their communities. Dubbed the National 9/11 Flag, it’s been traveling the country ever since — a journey for the country’s most recognizable symbol that has brought most Americans along, uniting more people in a post-9/11 world than it has divided in other times.

Within hours of the attacks, flags seemed to be everywhere: car windows, T-shirts, front porches. Wal-Mart sold 5 million by the spring of 2002.

Tolstyka, who served in the Army and organizes memorial motorcycle rides for veterans, went out and bought a flag for his car antenna a few days after Sept. 11. “It was a symbol,” he says, “of support.”

It was also a show of defiance against the terrorists, a rallying cry of unity and a soothing security blanket for a wounded nation.

“Every time there’s some kind of national emergency, we put up flags,” says Carolyn Marvin, a professor of communication at the University of Pennsylvania. “The flag represents the life of the country.”

The Stars and Stripes hasn’t always been as feel-good a symbol, depending on the decade and the politics. Defaced by Vietnam War protesters in the 1960s, invoked by politicians on both sides of debates about war and American values and burned by anti-American protesters overseas, it’s been alternately reviled and revered.

Few Americans flew the flag outside of homes or businesses in the first few decades of its existence, says Marc Leepson, who wrote a book called “Flag: An American Biography.”

But on April 12, 1861, when Confederates fired on Fort Sumter in Charleston, “flags started appearing almost overnight,” he says. Women wore them in hats, men put them in wagons.”

Leepson discovered an advertisement in a copy of a New York newspaper that was published just after the Fort Sumter attack. It mentioned a paint shop that advertised red, white and blue paints, and touted: “These colors are warranted not to run.”

After Sept. 11, 2001, the flag took on a larger-than-life symbolism and brought that unity to a grieving country. Bumper stickers with images of the flag and phrases like “these colors don’t run” became commonplace in parts of the U.S.

A New Jersey photographer snapped a photo of three city firefighters raising a flag on the ruined trade center site in an image that instantly was compared to the 1945 photo of U.S. Marines raising the U.S. flag at Iwo Jima. Flags spearheaded a patriotic buying boom, appearing outside homes, on office buildings, mugs and pins.

Country Singer Toby Keith wrote “Courtesy of the Red, White and Blue” one week after Sept. 11. The song led with Americans saluting the flag and described wreaking vengeance upon the country’s enemies:

“When you hear Mother Freedom start ringing her bell/And it’ll feel like the whole wide world is raining down on you/Ah, brought to you, courtesy of the red, white and blue.”

In December of 2001, Congress designated Sept. 11 as “Patriot Day” to honor those lost during the attacks — and mandated that all flags should be flown at half-staff each year on that day.

Nearly a decade later, flags aren’t hanging from every front porch anymore, but they fill many American blocks, and thousands follow the touring flags to touch something that connects them to Sept. 11.