Jimmy Carter, a US president who struggled with a bad economy and a hostage crisis but was widely admired in his post-White House career, was remembered during his state funeral as a man who put honesty and kindness above politics.

Hundreds of mourners on Thursday including all five living current and former US presidents packed the Washington National Cathedral.

As the sombre ceremony began and a bitterly cold wind blew, Carter's flag-draped coffin was carried up the stone steps of the cathedral by a military honour guard after its trip from the Capitol, where his body had lain in state for two days.

Fellow Democratic President Joe Biden was due to eulogise the 39th president, who died on December 29 at the age of 100.

Republican president-elect Donald Trump was among the luminaries at the funeral, before Carter's body was returned to Georgia, where Carter was raised as a peanut farmer.

Back to native Plains

Carter won the White House by defeating Republican President Gerald Ford in the 1976 US election, in the years following Richard Nixon's Watergate scandal.

Before the ceremony began, Trump entered the cathedral with his wife, Melania, Trump shook hands with his former vice president, Mike Pence, who he had clashed with after Pence refused to go along with his attempts to overturn his 2020 election defeat.

Canadian Prime Minister Justin Trudeau, Vice President-elect JD Vance and Biden's son Hunter were also among the mourners.

Former vice presidents Al Gore and Pence sat side by side.

Tens of thousands of Americans over the past two days filed through the Rotunda of the US Capitol to pay their respects to Carter.

Following the state funeral, Carter's remains will be returned to his native Plains in Georgia where he lived in his 44 post-White House years and made the base of operations for his diplomatic work and charitable efforts including Habitat for Humanity.