WASHINGTON — Simon and Garfunkel’s song “Sound of Silence,” which was written amid the turmoil following President John F. Kennedy’s assassination, will join Chubby Checker’s 1960s dance hit “The Twist” as two of 25 recordings selected for preservation at the Library of Congress.

These are just a few sounds of the 20th century being added to the National Recording Registry on Thursday for long-term preservation due to their cultural, artistic and historic importance. The library said Checker’s rendition of “The Twist” became a symbol for the energy and excitement of the early 60s after “American Bandstand” host Dick Clark chose Checker to record a new version of the song.

Later, the 1966 album “Sounds of Silence” by Paul Simon and Art Garfunkel was a hit in its day but not before the duo struggled and split early on. Their song “The Sound of Silence” from the aftermath of President Kennedy’s assassination 50 years ago this year had initially flopped — but it became a hit after it was re-edited as a single. That prompted the duo to reunite and quickly record another album under a similar title.

Garfunkel, 71, told The Associated Press he’s thrilled and flattered to have his work preserved in the Library of Congress. He said the hit album was a life changer for him and Simon. “Da da dee, da dee, da dee,” he sang in an interview.

“There’s something fundamentally appealing about the simplicity of those lines,” Garfunkel said.

“When you look at the little mesh, wire microphone ... and you address people on the other side of the mic, you hope that your performance will be special, and you hope that it will have lasting power,” he said, adding that he remembers thinking in the 60s that “if we do really good and give a very special performance to these great Paul Simon songs, we might last right into the next century and be appreciated.”

Their words and their tune have taken on special significance in American culture. Hearing Simon sing “The Sound of Silence” on the 10th anniversary of the 9/11 attacks, NBC newsman Tom Brokaw briefly struggled for composure. The music, he said, evokes memories.

This is the kind of impact the library was looking to preserve, “to celebrate the richness and variety of our audio heritage,” said Librarian of Congress James Billington in announcing the selections.

The recording that received the highest number of public nominations for this year’s registry was Pink Floyd’s “The Dark Side of the Moon.” The library said it was notable as an example of “brilliant, innovative production in service of the music.”

Other selections included the original 1949 cast album for “South Pacific” and the soundtrack to the popular 1977 movie “Saturday Night Fever,” starring John Travolta and featuring the Bee Gees, which revived the disco craze.

The selections span from 1918 to 1980 and represent nearly every musical and recording category.

Recordings by Will Rogers, Jimmie Davis and President Dwight D. Eisenhower capture part of the political climate of their eras. In 1931, Rogers’ radio broadcast at a low point in the Great Depression included a folksy chat with President Herbert Hoover to kick off a nationwide unemployment relief campaign. Davis’ 1940 recording of “You Are My Sunshine” became his election campaign theme song while running for governor of Louisiana. It became one of the most popular country songs of all time and the state song of Louisiana in 1977.

Eisenhower’s voice was carried in a prerecorded message in 1958 carried by the first communications satellite launched on a U.S. rocket. Eisenhower’s message of peace to the world transmitted from space was touted as a victory in the space race after the Soviet Union launched a satellite the year before.

Van Cliburn’s Cold War piano performance in Moscow when he won the prestigious Tchaikovsky International Piano Competition at 23 also was selected. At the time in 1958, Time magazine noted his appearance and tour of the Soviet Union “has had more favorable impact on more Russians than any U.S. export of word or deed since World War II.”

Earlier this year, the Library of Congress unveiled an extensive plan to help libraries and archives nationwide preserve recorded sound to guard against losing historic recordings. It’s proposing 32 recommendations to Congress on actions to preserve endangered audio.

For his part, Garfunkel said he’s still working, writing poems, putting together a book and singing. He said he’s working to regain his voice after having vocal troubles. And he said he’s ramping up to get back to the stage and wouldn’t rule out a reunion with Simon when the time is right.

“Who knows what the future brings?” Garfunkel said. “This is my old buddy, the first friend I made in life.”