The actor is in Minot to raise funds for relief efforts after floodwaters forced 11,000 people from their homes, damaging thousands of properties and businesses.
Duhamel visited flood victims in a Red Cross shelter and also surveyed the damage across town - his childhood home was severely damaged and his middle school is rotting after remaining underwater for weeks.
He tells the Associated Press, "It's unbelievable how much devastation a flood like this does."
But the Transformers star, who has also organised a benefit concert for Saturday (03Sep11), is confident the locals will be able to rebuild Minot.
He adds, "I have pride in where I'm from and just want to help the best way I could. People (in Minot) are as strong as they come. I'm not really worried about the will or spirit of the people."