Schools were closed because of the cold as far south as Iowa, and authorities in Grand Rapids, Mich., issued an extreme cold weather alert and went out urging the homeless to seek shelter.

The weather service warned that exposed flesh can freeze in 10 minutes when the wind chill is 40 degrees below zero or colder.

Temperatures in Minnesota were minus 40 in International Falls and minus 35 in Roseau. Farther south, Minneapolis hit 18 below zero with a wind chill of 32 below and black ice was blamed for numerous accidents.

Back in Hallock, Mark Johnson, vice president of Johnson Oil Co., said the extreme cold isn't too bad, and once it gets to a certain point, the degrees don't matter. For example, he said, 38 degrees below zero isn't much different than 24 degrees below zero.

"We're kind of acclimated to it up here up in this country," he said. "Each year, sometime during the winter, it's going to get to this point. Just as long as it doesn't stay like this for a whole month, you can deal with the day-to-day getting through it."