After the war, Hahn worked for the U.S. Postal Service, later moving to Nebraska to be closer to his family, KETV reported.
Hahn said he received birthday cards from government officials and President Donald Trump.
"It's unbelievable," Hahn told the television station.
Hahn said his secret to living to 100 is to "be kind, be careful, and be cautious," KETV reported. He also makes clocks out of steering wheels, tends a tomato garden and enjoys board games.
"It amazes me that he just keeps going and going," Hahn's son, Gary Hahn, told the television station. "He's sharp and he likes to keep busy."