The president met the mayor on Wednesday and did not know he is just 24 years old.
They met while the president stopped at Orion Energy Systems, a plant that manufactures low-cost, energy-efficient lighting.
The president joked and said the mayor seemed a bit young for the job.
"He says he's the mayor of Manitowoc. I'm looking at the guy, and I don't think it's true," Obama said.
Mayor Justin Nickels said Obama told him it's great to see young people getting involved in their communities.
