Enter the names of the U.S. Presidents who were the only living U.S. President for a period of time. (Do not include future presidents being alive, only those who had served already or currently serving).
Imagine if tomorrow, Carter, G.H.W. Bush, Clinton, G.W. Bush, and Obama died in a plane crash. The remaining living person that has been president of the U.S. would be Donald Trump. Therefore, Trump would be the only living U.S. President (current or past), until a new president was elected. Then there would be 2 living presidents, Trump and whomever was elected as the new president.
An update on your comment about former presidents. Both Jimmy Carter and George H W Bush have died so that leaves just Bill Clinton, George W Bush, Barack Obama, Donald Trump, and Joe Biden as the former exes still living as of 6/7/25.
This scenario is less likely to happen nowadays when two ancient presidents (Biden and Trump) followed youngish ones...