Most customers were expected to have power back later in the day, but some customers would likely have to stay in the dark through the weekend, utilities said.
Some 63,500 Michigan homes and offices remained without power early Friday after a weekend ice storm struck much of the state.
The storm moved across much of the northern tier of the nation and southern Canada Saturday and Sunday, leaving up to 2 inches of ice in some areas, causing traffic accidents and freezing power lines.
Temperatures in many areas remained below freezing, so electrical lines remained covered in ice, which caused more blackouts, energy companies said.
"Ice storms differ from thunderstorms because the damage from ice often continues for several days," DTE Energy Co. in Detroit said in a storm update to customers late Thursday.
"A quarter of an inch of ice is the equivalent of 500 pounds of weight on a span of power line," the utility said. "In some areas, as much as three-quarters of an inch has been found on DTE Energy power lines."
Some 8,000 DTE customers in southeast Michigan were still without power, down from 150,000 customers who lost power in the storm, the utility said.
Michigan's largest utility, Consumers Energy, reported 55,500 customers without power as of 9 p.m. Thursday, down from 368,000 outages.
Crews from as far away as West Virginia and Georgia were working 16-hour shifts in Michigan to repair power lines.
Central Maine Power Co., the state's largest, said at 9 p.m. 11,000 customers were without service, down from a Tuesday's 87,000 peak. But it said more than 123,000 customers lost power at least once in the catastrophic storm's aftermath.
The icy conditions were described in some regions as the worst in at least a decade, the Wall Street Journal said.
Outages in southern Canada included parts of the provinces of Ontario and New Brunswick.
Toronto Hydro Corp. reported about 46,000 customers without power Thursday night, down from 300,000 Sunday. Hydro One Inc. reported 7,500 customers still with no electricity, mostly in Guelph, Orangeville, Bolton, Dundas and other parts of southern Ontario.
Utility workers in New Brunswick reported fewer than 19,000 customers without power, but NB Power said it could take until Tuesday to completely restore power.
The utilities said the restoration process was labor intensive because of a focus on individual neighborhoods and streets.
Meanwhile, temperatures were summer-like on the U.S. West Coast, reaching 83 degrees Fahrenheit in Long Beach, Calif., Thursday afternoon and 79 at Los Angeles International Airport, the National Weather Service said.
The Long Beach temperature topped the 1976 record high of 79 degrees.
Beaches in Long Beach had near-summer-type crowds, the Press-Telegram of Long Beach reported.
"It's like summertime," Marcelo Cavalcanti, who bought his daughter a cotton-candy flavored ice cream, told the newspaper.
"Today we're riding bikes and spending time with the grandparents. It's a perfect day. I feel like jumping in the ocean," he said.