Carter met with Kim Il Sung, North Korea's founder, in 1994, more than a decade after leaving office.
Kim Il Sung, who died weeks after meeting with Carter, is the grandfather of current leader Kim Jong Un.
Clinton was invited to meet with Kim Jong Il, Kim Il Sung's son, and successor, in 2000 but declined the invitation.
Instead, then-Secretary of State Madeline Albright went to North Korea.
It wasn't until nine years later when Clinton himself, then out of office, met with Kim Jong Il as part of an effort to help secure the release of two U.S. journalists, Laura Ling and Euna Lee.
Former Vice President Al Gore met Ling and Lee when they returned to the United States.
That wasn't the last time that a former president met with North Korean officials to help free an American. In 2010, Carter returned to North Korea on behalf of Aijalon Gomes, a Massachusetts resident who was sentenced to eight years of hard labor for entering the country illegally.
Carter returned to the so-called hermit kingdom in 2011, this time along with other world leaders as part of talks about the country's food shortage.
In recent years, the most notable U.S. visitor to North Korea has been former basketball star Dennis Rodman.
Rodman visited the country in 2014 and once again in 2017.