Roads remained treacherous Saturday after a powerful winter storm moved through Minnesota. Roads are "covered in black ice" and visibility is limited, the Minnesota State Patrol warned, imploring drivers to slow down and buckle up. Windchill advisories and warnings were in place, with windchills in the -30s across the state.

Statewide, between 4:30 p.m. Friday and 11:30 a.m. Saturday, there were 350 crashes, 30 with injuries, 282 spin outs and one jackknifed semi, the patrol said.

Ferocious winds that pounded nearly every corner of Minnesota on Friday whipped up whiteouts and led state and county agencies to shut down thousands of miles of highways that in calmer conditions would have hummed with holiday travelers.

Instead, most roads were empty as a blizzard packing winds in excess of 50 mph reduced visibility and pushed snow back onto plowed lanes. Several counties in southern Minnesota took plows off the roads until conditions improved, the National Weather Service said.

The Minnesota Department of Transportation reopened Interstate 90 between Albert Lea and the South Dakota border, but advised that road conditions are still difficult.

MnDOT also said "no travel" advisories will be lifted on several highways across south central and southwest Minnesota, but some remain closed as snowplow crews continue working to clear drifts. MnDOT advises drivers to check 511 for the latest conditions.

Metro Transit said 43% of buses were delayed, by an average of nine minutes, at noon Saturday, while light rail has "stabilized."

Widespread and prolonged periods of whiteout in frigid conditions led scores of motorists to stall or land in ditches across south and south-central Minnesota. Troopers had to remove several vehicles from the ditch along Hwys. 71 and 68 south and west of Redwood Falls, said Sgt. Troy Christianson with the State Patrol.

"First responders are swamped," said Minnesota Department of Transportation spokeswoman Sandra Schlagel. On Friday afternoon, Gov. Tim Walz declared a peacetime emergency in response to the storm, activating the Minnesota National Guard to assist with rescuing motorists.

Conditions were bad enough that Meeker County in central Minnesota and Freeborn, Jackson, Mower and Blue Earth counties in southern Minnesota pulled plows off roads Friday afternoon.

Travel was not advised across much of the west, southern and central parts of the state, where a blizzard warning remained in effect until Saturday morning. Winds consistently howling between 35 to 50 mph made for tough going, even in the southern metro counties of Dakota and Scott, also included in the blizzard warning.

"You create your own emergency if you stall, spin out or crash," said Anne Meyer, another MnDOT spokeswoman. "That is why we don't want people going out when travel is not advised."

Few people were out and about in Blue Earth, where the lack of traffic on I-90 made for a slow morning at the Farmer's Daughters Kitchen about 40 miles west of Albert Lea. The eatery located just off the freeway is normally packed for Friday breakfast, said owner Becki Steier.

"We had some customers this morning, but it's quiet now," she said. Scores of trucks were idled at a truck stop across the street, she said.

Down the road in Fairmont, Hannah Johnson, a property supervisor at the Quality Inn, said she'd seen only a handful of travelers make reservations to get out of the blizzard. Likewise, she saw just a few vehicles on the road while she was out shoveling.

Johnson said she didn't mind the blizzard. "It's going to be Christmas soon, and we're going to have all this snow."

The North Pole-like weather was felt along the North Shore of Lake Superior. Grand Marais had the second-strongest wind gust ever recorded at the harbor, clocked at 74 mph Friday morning, according to the Weather Service in Duluth.

Slick conditions in the Twin Cities led to crashes and spin outs all day, MnDOT said.

Air travelers suffered for the second straight day as close to 5,000 flights were canceled nationwide by Friday afternoon. At Minneapolis-St. Paul International Airport there were 157 cancellations of incoming or departing flights by 3 p.m., according to the flight tracking website flightaware.com.

Amtrak scrubbed Empire Builder runs between Chicago and Seattle through Sunday. The train stops at Union Depot in St. Paul. Metro Transit buses were rolling, but many were running late.

Travelers weren't the only ones experiencing setbacks. UPS, Amazon and FedEx officials said severe weather could cause delays for Christmas deliveries.

Philip Ekman, owner of Albertville-based Platinum Courier Service, said the weather had not slowed the 20 drivers he employs.

"For the most part, they're pretty hardy people," he said.

But the heavy snow and intense cold prompted customers to scale back on deliveries that were not considered essential and could be postponed, Ekman said.

For Christmas presents that needed to be delivered on time, Ekman said Platinum was not slowing down. One of his drivers picked up an expensive watch at the Minneapolis-St. Paul International Airport and was on the road to deliver the gift in Michigan, he said.

With frigid conditions expected to continue into next week, CenterPoint Energy and Xcel Energy asked customers to consider temporarily lowering thermostat settings to conserve energy and save on heating bills. Both utilities said they were seeing a short-term rise in natural gas market prices due to the extreme cold across much of the country.

"Consider conserving natural gas for the next few days, because the wholesale cost is passed on directly to customers," read a statement from Xcel Energy.

CenterPoint Energy recommended settings at 65 degrees during the day and 60 degrees when asleep or away from home.

Sunday should bring a sunny Christmas morning, with temperatures in the single digits and a chance of snow toward evening. By midweek, a thaw could mean highs above freezing Wednesday and Thursday.

Staff writers Trey Mewes and Burl Gilyard contributed to this report.