Nobel laureate Jimmy Carter, who has lived longer than any U.S. president in history, celebrates his 100th birthday today.

Carter, a Democrat, served a single term as president from January 1977 to January 1981. His decades of humanitarian work after leaving office, including the promotion of human rights and alleviating poverty in countries around the world, earned him the Nobel Peace Prize in 2002.

His birthday, which comes 19 months after he entered hospice care at his home in Plains, Georgia, is being marked by the broadcast of a tribute concert by stars of country, rock and gospel music recorded at Atlanta’s Fox Theatre last month. The concert raised more than $1 million towards the international programs of the Carter Center, which he founded with his wife, Rosalynn Carter. The former president plans to tune in to the concert on Georgia Public Broadcasting, according to his grandson Jason Carter.

Jimmy and Rosalynn Carter were married for 77 years. Rosalynn Carter died in November 2023 and the former president was last seen in public at his wife’s funeral, where he used a wheelchair and appeared frail.

He has been diagnosed with cancer and other health issues, and decided to end medical intervention and enter hospice care in February 2023.

In a birthday tribute, U.S. President Joe Biden, a Democrat, said Carter had always been “a moral force for our nation and the world.”

“Your hopeful vision of our country, your commitment to a better world, and your unwavering belief in the power of human goodness continues to be a guiding light for all of us,” the statement said.

The Carters have worked with the non-profit group Habitat for Humanity International since the 1980s, and the former president has regularly joined other volunteers to help build homes for people affected by poverty or disasters.

This week, to mark Carter’s birthday, scores of Habitat volunteers, including country music stars Garth Brooks and Trisha Yarwood, will build 30 homes in St. Paul, Minnesota, the group said.

“The Jimmy & Rosalynn Carter Work Project serves not only as a way to honor the Carters’ legacy, but also as a reminder of what is possible when people from all walks come together to work toward one common goal,” Jonathan Reckford, Habitat’s chief executive officer, said in a statement.