DENVER -- A heavy, wet spring snowstorm forced airlines to cancel scores of flights at the Denver airport on Wednesday and left thousands of people without power.

Tree branches sagged and snapped under the weight of the snow. Dozens of schools canceled classes and the state Legislature declared a snow day, canceling House and Senate sessions as well as committee meetings.

Traffic was light for Denver's morning rush.

"Some folks maybe decided they didn't have to travel, so they just stayed home," said Gene Towne of the Colorado Department of Transportation.

The National Weather Service said 23 inches of snow fell by Wednesday morning in Jefferson County west of Denver and about 9 inches in Denver.

The storm boosted the mountain snowpack, which accounts for much of Colorado's water when it melts during the warm months. As of Wednesday, the snow totals were below average in the northern half of the state and roughly average in the south.

Denver International Airport estimated up to 5,000 people spent Tuesday night there after their flights were canceled Tuesday. Airport workers passed out cots and blankets.

The airport's three busiest airlines -- United, Frontier and Southwest -- together canceled nearly 150 arrivals and departures Wednesday.

The airport planned to keep three of four runways open Wednesday during the busy spring season, with one runway closed on a rotating basis for snow removal.

Xcel Energy said about 7,500 customers, mostly in the Denver area, were still without power Wednesday morning. About 45 crews were working to restore power by 5 p.m. About 36,400 customers lost power at various times after snow started falling Tuesday, Xcel Energy spokesman Tom Henley said.

Barbara Foley, 70, of Englewood rode the bus to work Wednesday in downtown Denver after she woke up to find about a foot of snow on her car. She was happy the bus arrived on time, with a driver in a good mood.

"I told the driver, 'You're just as good as the mailman,"' she said. "He said, 'No, lady, we're better."'

In the mountains, U.S. 6 over Loveland Pass was closed for avalanche control and because of hazardous conditions. Farther west, Colorado 65 near Grand Junction also was closed for avalanche control.

On the plains in southeastern Colorado, a jackknifed semitrailer and snow closed U.S. 287 between Springfield and Lamar.