DENVER —  The United States' fifth-busiest airport, which shut to all flights Wednesday, wasn't expected to reopen until noon Friday, creating a ripple effect that disrupted air travel around the country just as the holiday travel crush began to build.

The closure of Denver International — once touted as an "all-weather airport" — prompted cancellation of more than 2,000 flights through Friday, according to airline officials.

• Click here to see FOXNews.com's Colorado snowstorm photo essay

Nearly 5,000 travelers had been stranded at the airport. But by Thursday afternoon, buses and shuttles were making regular pickups, and a steady flow of people headed toward the parking lots. By nightfall, about 1,500 remained, spokesman Steve Snyder said.

On Wednesday night, airport authorities provided a few hundred cots for the estimated 4,700 stranded travelers and doled out scratchy Red Cross blankets, along with diapers and baby formula.

It was the biggest snowstorm to hit Colorado since a March blizzard in 2003 that shut down the region and killed six.

Some mountain areas got more than 3 feet of snow, and up to 25 inches fell in the Denver metropolitan area.

Despite the slick roads and deep drifts, there were no immediate reports of any deaths or serious injuries reported.

Denver's normally bustling downtown was all but empty Thursday, with a few people trudging down the middle of unplowed streets.

The storm — which lingered through midday Thursday — also shut down major routes through the West. It moved eastward Thursday afternoon, snarling air and road travel in Nebraska and Kansas.