Snow driven by wind up to 69 mph fell from North Dakota to the Texas Panhandle, shutting down schools, post offices and South Dakota state government.
Four deaths were blamed on slippery roads in South Dakota, Nebraska and Kansas, and a fifth person was killed when tornado picked up and hurled a car in Arkansas.
"It's not safe for anybody," said Sharon Rouse, owner of a towing service in Kearney, Neb.
The storm's worst might not be over, Dennis Feltgen of the National Weather Service told CBS News Radio.
"They're still getting some wind gusts as high as 45 miles per hour, 60 miles per hour and that's drifting some of the snow up to six feet in some areas of eastern Colorado," Feltgen said.
Eastbound lanes of Interstate 70 were closed for nearly 350 miles from Denver across the Plains to Russell, Kan. Westbound lanes were reopened in some areas.
"We're just waiting," said Corey Dagner, who was stuck in Limon, Colo., on his way home to Illinois after attending a wedding at the Breckenridge ski resort. "Nobody's sure what's going on and what time they're going to open the interstate."
Denver International Airport was spared, and had an estimated 158,000 travelers Sunday, one of the busiest travel days of the year. "We had some wind, that's it," said airport spokesman Chuck Cannon.
Motels in Limon, 70 miles east of Denver, filled up quickly Sunday night. About 50 people who could not find or afford a room took refuge at First Baptist Church, sleeping on pews or in classrooms. Most left Monday morning in search of another route home.
"We're just a place where people get stranded in storms," Pastor Rick Taylor said. It happens two or three times a year, he said.
The Colorado portion of I-70 was dry Monday, but the highway was impassable in western and central Kansas because visibility was nearly zero. Colorado halted eastbound traffic because there are so few places to stop and wait on the state's sparsely populated eastern plains.
Almost 1,000 people spent Sunday night in shelters along I-70, said Joy Moser, a spokeswoman for the Kansas Division of Emergency Management. Even though the blizzard warning for northwest and north-central Kansas expired Monday afternoon, shelters remained open in anticipation of more stranded travelers.