José Feliciano sings the national anthem during the National League baseball championship series in 2012.

Although “The Star-Spangled Banner” is performed before every baseball game and at many other public events, it’s notoriously hard to sing. But in its history, the song has allowed the performers who can sing it to create memorable and unique interpretations of the United States’ most prominent musical symbol.

When “The Star-Spangled Banner” became the national anthem in 1931, the New York Herald Tribune famously described it as “words that nobody can remember to a tune nobody can sing.” Its melody is adapted from an 18th-century drinking song, and its lyrics from a poem that Francis Scott Key wrote 200 years ago (describing a battle in the War of 1812). And it’s fiendishly hard to hit all the notes — the highest is an octave and a half above the lowest.

A 2004 poll found that only 39 percent of Americans could correctly complete the song’s third line.

Franklin Bruno, songwriter and author of a forthcoming history of songwriting, The Inside of the Tune, points out that the anthem anticipated the country’s musical future in the way the rhythm and rhyme scheme of each verse’s third couplet (“And the rockets’ red glare, the bombs bursting in air …”) change the song’s tone by softening the martial quality of the other lines.

“It’s fitting that our national anthem wouldn’t be in quite the strict English ballad form,” Bruno said.

The national anthem’s symbolic weight also means that when it is performed in anything but a straightforward way, listeners ascribe meaning to the deviation. On July 4, 1941, against the backdrop of World War II, composer Igor Stravinsky premiered an orchestral arrangement of the anthem that incorporated a few unusual harmonies. That performance led to a brief skirmish between Stravinsky and Boston police, who thought he’d violated a state law against “tampering” with the national anthem.

During the 1968 Major League Baseball World Series, Puerto Rican singer José Feliciano performed “The Star-Spangled Banner” in the style of a contemporary folk-pop song, accompanied by acoustic guitar. It caused a flurry of controversy: “Some people wanted me deported,” he later said, “as if you can be deported to Puerto Rico.” (Puerto Rico is a territory of the United States.) But Feliciano’s version became a minor hit single, and he said that by the time he reprised his version at a 2012 championship baseball game, it was generally understood by the audience as “an anthem of gratitude to a country that had given me a chance.”

Marvin Gaye’s slow, spectral, gospel-tinged rendition performed at the 1983 National Basketball Association All-Star game, accompanied by a drum machine, made the song sound shockingly modern. Former Los Angeles Lakers star Earvin “Magic” Johnson said Gaye’s performance gave him a feeling of “pride at being an American ... you almost cried, it was so devastating.”

While singing “The Star-Spangled Banner” is most often a statement of national pride, it can also be a vehicle for political protest. A 2006 Spanish-language recording of the song (as “Nuestro Himno”) criticized American immigration policy.

Jimi Hendrix famously performed his rendition of the anthem at the 1969 Woodstock music festival as a protest against the Vietnam War. Complete with “bombing” sound effects, it is the best-known radical reworking of the anthem. “It’s not unorthodox,” Hendrix told television interviewer Dick Cavett in September 1969 about his interpretation of the anthem. “I thought it was beautiful.”

At the time of the 1991 Super Bowl, when Whitney Houston sang “The Star-Spangled Banner” — with a flourish on the high note of “land of the free” that propelled it even higher — America was in the middle of the Gulf War, and she dedicated her performance to the country’s military. It became a hit when it was released as a single a few weeks later. It was even more successful when it was re-released a decade later, with proceeds to benefit New York firefighters and police after the September 11, 2001, attacks. Beyoncé Knowles’ recent performances of the anthem (at Barack Obama’s 2013 inauguration, among other venues) have loosely followed Houston’s template, including its extra-high note.

That the anthem is hard to sing may be apt; Americans enjoy freedoms that have not come easily. Over time, “The Star-Spangled Banner” has become a song that invites expressions of individuality and of unity. There’s something fitting about that, too.