If all five living United States presidents attend the state funeral service for former President George Bush on Wednesday, it will be one of a small number of times that this many of them have been in the same place at the same time.

There have been at least five of these rare gatherings since 1991.

In fact, there was only one period in United States history before then, around 1861, when more than five presidents were even alive at the same time.

[Here are the highlights of former President George Bush’s funeral in Washington.]