Let’s imagine that Franklin D. Roosevelt had possessed the same gift for longevity as Jimmy Carter and lived until he was 100. He would have died in1982, in Ronald Reagan’s second year in office.

Jimmy Carter, the 39th President of the United States, will be eulogized at a state funeral Thursday at the National Cathedral and later by private family services and interment in Plains, Georgia.

It is unusual for five current and former presidents to gather at the same event, but when it happens, it is often at a funeral.