William Whenham, 24, drove his silver Ford pickup along a slushy stretch of State Highway VV in Missouri's Cass County, outside of City. Son Colton, 6 months, rode in the backseat, strapped into his car seat.
Whenham lost control of the truck just after 8 a.m.
"The truck traveled down an embankment, overturned and came to rest into a creek," said Sgt. Collin Stosberg of the Missouri State Highway Patrol.
Whenham freed himself and saved his son, who was submerged for around a minute. When emergency personnel arrived, the pair were already ashore.
Father and son suffered hypothermia, and Whenham sustained minor injuries. Colton remains at Children's Mercy Hospital in Kansas City. Hospital spokeswoman Jessica Salazar told AOL News the boy's condition is good.
Stosberg said the story is a testament to the power of seat belts.
"It could have been tragic consequences had he not been buckled up," said Stosberg, who educates Missourians about seat belt safety. The belt likely saved Whenham's life and allowed him to save the life of his son.
"I often hear, 'What if I go into the water?' But how are you going to survive that initial impact?
"Crashes happen. The moral of the story is, he was able to unbuckle himself and do what he needed to do and save his infant son," Stosberg said.