About 586,000 customers were without power by late Wednesday night, down from a peak of 849,000 earlier in the day, Gov. Tom Corbett said in a briefing at the headquarters of the Pennsylvania Emergency Management Agency outside Harrisburg.
Corbett said he has signed a disaster emergency proclamation, freeing up state agencies to use all available resources and personnel.
"People are going to have to have some patience at this point," Corbett said, warning that an overnight refreeze could cause more problems on the roads Thursday.
PECO, which was working to restore power to more than 500,000 customers, warned that it could take until the weekend for some people get their electricity back.
The storm piled up to a foot of new powder along the state's northern tier and coated the southeastern quadrant with a layer of ice that gave trees a picturesque, frosty sheen but brought down limbs and trees from Gettysburg to Philadelphia.
Long stretches of the Pennsylvania Turnpike were under speed and trailer restrictions all morning, but those rules were lifted as the weather warmed and some melting began.
A fatal crash shut down the turnpike in both directions outside Harrisburg for more than 13 hours, and turnpike officials also warned motorists to watch for fallen trees in eastern Pennsylvania. A crash involving a tractor-trailer and the Army women's basketball team charter bus, which had been scheduled to play Lehigh University in Bethlehem, sent more than a dozen players to local hospitals to be checked out for what officials said were non-life-threatening injuries.
Several hospitals in the Philadelphia suburbs were running on backup power, forcing most to reschedule elective surgeries and outpatient procedures.
Amtrak suspended its Philadelphia-to-Harrisburg service because of downed trees on wires and along tracks, with no estimate of when it would be restored. The Southeastern Pennsylvania Transportation Administration reported delays and some cancellations on its suburban routes and urged transit riders to use caution and delay commutes if possible until conditions improved.
Customers at Weist Hardware in New Cumberland, across the river from Harrisburg, made a run on metal shovels, snow scrapers and the store's supply of 10-pound bags of ice melt.
"We had a whole mountain high in the back, and that went in the last two days," said store owner Audrey Weist.
In Hamburg, the storm deposited a quick couple inches of snow and sleet, followed by a cold, persistent rain that coated tree branches, parked cars and other untreated surfaces in a layer of ice while turning roads slushy and slick.
John Balthaser gunned his pickup as he plowed the parking lot of an RV dealership, trying to pick up a head of steam to push mounds of very heavy slush into a bank.
"It just wants to push your truck all over," he said. "It's getting harder and harder to push as the rain comes on."
Reading cafe owner Mark Hazer made a pit stop to get gas and characterized his commute to work this way: "It was wet, icy and dangerous."
"I'd rather be home sleeping," Hazer said with a laugh, but "I gotta go to work, that's the thing."
Philadelphia International Airport reported more than 100 cancelled flights early Wednesday but continued its normal operations with all four runways open.
Many school districts announced delays or canceled classes entirely. Having lost power and with no heat in its dormitories, Villanova University shut down for the rest of the week and urged students to make arrangements to go home.
Pittsburgh and surrounding areas were dealing with about three inches of snow, topped by ice created by freezing rains that began falling before dawn. Most roads were plowed and passable, though black ice was a consideration in spots as the freezing drizzle continued in spots as the morning rush hour began.
Associated Press writers Peter Jackson in Harrisburg and Michael Rubinkam in Hamburg contributed to this report. Scolforo reported from Harrisburg.