World war I is another story entirely. There is just one surviving U.S. veteran of the Great War - Frank Woodruff Buckles.
Albert Woolson, who died in 1956 at the age of 106 was the last surviving Civil War veteran.
Anson Wolcott Gillett didn't live quite that long. Born in 1845, he served three enlistments, then spent the rest of his career in the directory and advertising business. He was one of Blackhawk County, Iowa's last remaining Civil war veterans when he died in 1937.