With the passing of GHWB this week, I came across something that I found very odd.
Currently, there are four former POTUSes still living (I'll let you the reader figure out who they are). Did you know that there have been only six times in US history (outside of President Washington) where there have been no living former presidents?
John Adams was the first, as Washington died before he left office. There wasn't another until Ulysses Grant's term, where Andrew Johnson passed before Grant left office - and all other presidents had died by that time. Grover Cleveland saw this happen during his second term in the White House (aside: he is considered both the 22nd and 24th President, as he was the only one to serve non-consecutive terms in office). Next was Teddy Roosevelt, who became President on the death of William McKinley. Before leaving office, all of his living predecessors in the job had passed on. Herbert Hoover was next, as his predecessor Calvin Coolidge had passed away and all the other presidents between Roosevelt and Warren Harding (who had died in office) were also dead.
However, the longest (and now most recent) period where there were no living former presidents was from January 23, 1973 to August 9, 1974. This time frame (from the date of Lyndon Johnson's death to Nixon's resignation) was the longest that the USA went without a former living president.