If any of our founders were still alive, they'd probably be almost 190 years old
But I'm not really sure which of our founders was the longest living... that would be interesting to know. I know of one that was still living in 1884 and would have been about 70 years old at the time -- Stephen J. Field, who was a supreme court justice. He is probably one of the longest living DU founders, but there were 29 others so I'm not sure.