The unthinkable is being thought among those close to Jimmy Carter.

The former president, who entered hospice care 16 months ago, may make it to his 100th birthday on Oct. 1. Some are making plans to mark the occasion.

Among them is Jill Stuckey, a family friend and superintendent of the Jimmy Carter National Historical Park in the former president’s hometown. She said she visits with him nearly every day.

“I think he is going to make it to 100,” Stuckey said. “I don’t know that he is saying that, ‘I’m going to live to 100.’ But I do know there is will to live in all of us, and I think he has that same will.”

When Carter entered hospice care in February of last year, doctors told the family he might have only days to live.

About 500 days have passed since then.

Carter has outlived Rosalynn Carter, his wife of 77 years, who entered hospice nine months after he did and died in November. The former president hasn’t made a public appearance since her funeral. Instead, he remains inside the couple’s modest home in Plains in south Georgia. Still, he cast a mail-in ballot for the primary election in May.

He has already lived longer than any U.S. president in history.

Recognitions for Carter’s centennial include a 100-mile community bicycle ride in his home county and a free film festival in Atlanta organized by the Jimmy Carter Presidential Library and Museum.

“We have always planned to celebrate the 100th anniversary of his birth, and it just makes it even more special that he is still with us,” said Tony Clark, a spokesperson for the Atlanta-based library.

Staff are still working out some of the plans. But locked in is an indoor and outdoor film festival at the presidential library on Sept. 28, the Saturday before Carter’s birthday, from 10 a.m. to 10 p.m., featuring some of his favorite movies while in office.

According to the library’s records, hundreds of movies were shown at the White House during his presidency, including All the President’s Men, Rocky, One Flew Over the Cuckoo’s Nest, The Blue Lagoon, Caddyshack, Kramer vs. Kramer and Mr. Smith Goes to Washington. He watched parts or all of at least some of the films.

While Carter was Georgia’s governor he helped create an economic development push to film more movies in the state. He has another important connection to the big screen. Carter’s first date with Rosalynn Carter was at the movies. The next morning he told his mother he had found the person he would marry.

Admission to the library will be free on the day of the film festival. And on Oct. 1, Carter’s actual birthday, the library will follow its tradition of having the admission price match the president’s age: $1.00. (Last year on his 99th birthday, it was 99 cents.) As always, kids 16 or younger get in free.

The library and museum also intends to have a new exhibit about Carter’s 100 years, including documents, photos and art that haven’t been on display at the facility before, Clark said.

The adjacent Carter Center, the nonprofit that the former first couple founded to improve health, encourage freedom and spread peace globally, has yet to disclose how Carter’s birthday will be celebrated. The center’s chief executive, Paige Alexander, offered little more than a one-word hint: “music.”

“Music was an important part of his life. It will have something to do with that,” she said.

Habitat for Humanity, the Georgia-based homebuilding nonprofit that the Carters championed for more t

han three decades, already does a special building push each year coinciding with the former president’s birthday. This year the weeklong Jimmy and Rosalynn Carter Work Project will be in St. Paul, Minnesota.

Alexander said this past week that there hasn’t been a change in Carter’s condition. She told the Atlanta Journal-Constitution’s “Politically Georgia” in May that he was “enjoying peanut butter ice cream.”

Jason Carter said on the AJC’s Monica Pearson Show in May that he recently told his grandfather that he’s never sure how to respond when asked how the former president is doing.

“He kind of laughed a little bit, and he looked at me, and he said: ‘I don’t know myself,’” Jason Carter told Pearson. “But I think he’s OK. You know, he’s hanging in there, and he knows he’s not in charge. So he’s just waiting for what’s next.”

Groups in Carter’s hometown of Plains are still sketching out plans for how to pay tribute around the time of his birthday.

Sumter Cycling, a nonprofit of southwest Georgia cyclers in Carter’s native Sumter County, typically holds a nearly 50-mile bicycle ride to coincide with the Plains Peanut Festival, which this year falls on the Saturday before Carter’s birthday. Now organizers are hashing out plans to more than double the Plains, Trains and Bike Chains ride to 100 miles in recognition of the former president’s big day.

The nearby Jimmy Carter National Historical Park is planning a riff on the Carters’ frugality. Staffers are putting together a list of 100 ways to save time, energy and money.

“That’s near and dear to the Carters’ hearts,” said Stuckey, the park’s superintendent.

Editor’s note: A list was updated to reflect that Joe Biden recently passed Richard Nixon as the 10th longest-living president.