NEW YORK -- The eight states hit by the worst blackout in U.S. history face their first major test of recovery today as millions of people return to work, reboarding commuter trains and powering up businesses that were shuttered in the darkness.
In several areas, energy companies warned customers to conserve as demand for power spikes again. Even though only three of the nine U.S. nuclear plants that shut down during the blackout were expected to be running by the morning rush.
"We're still stabilizing our system. We're still asking our customers to conserve energy wherever possible," said Consolidated Edison spokeswoman Joy Faber.
In Canada, where a large part of Ontario also lost power, officials pleaded with businesses, industry and the public to reduce electricity use by 50 percent.
"If people don't cooperate, the system will break," said Jim Young, Ontario's commissioner of public safety.
In the United States, energy experts with the North American Electric Reliability Council said they didn't expect a need for such public appeals, or for rolling blackouts, despite the increasing power use.
However, the council said New York would re-evaluate whether to issue an appeal this morning. State energy experts say power consumption is expected to increase by about 12 percent from Sunday to Monday.
The massive blackout that hit Thursday afternoon and lingered into Saturday in some areas cost New York's economy hundreds of millions of dollars, and contributed to at least five deaths. But Mayor Michael Bloomberg and other officials were upbeat as the work week approached.
"It is basically business as usual," Bloomberg said Sunday. "We expect no problems tomorrow morning, other than the normal stuff."
Still, the system remains "a little delicate," said Long Island Power Authority chairman Richard Kessel.
"We ask that people don't go crazy using electricity on Monday, because that could create a lot of problems."
Throughout the city Sunday, business owners sized up their losses.
"It's serious," said Pando Andonopulo, who has run the Ninth Avenue Cheese Market for 30 years and said he lost hundreds of pounds of cheese, prepared salads and sandwiches. "Maybe I'm not going to be able to pay my rent."
At the Big Apple Meat Market, assistant manager Jose Gonzalez said the blackout cost the business tens of thousands of dollars. Hundreds of pounds of rotten meat sat in shopping carts in a refrigerated room, where it will be inventoried for insurance purposes.
City sanitation workers were dealing with overflowing garbage cans and mounds of bags filled with spoiled food.
Transportation officials said airlines, subways and commuter trains were running on schedule Sunday, and Mark Groce, a spokesman for NYC Transit, said subways should run on schedule today. However, Grand Central Terminal and some 2,000 other Con Ed customers were still without steam power for air conditioning and hot water Sunday, though the utility expected to have it restored by morning.
Bloomberg said Sunday that the city would put together a task force to study "what did we do right, what did we do wrong, how could we have done things better" -- including investigating brief interruptions in communication between dispatchers and emergency personnel during the blackout.
"We absolutely did a great job," the mayor said. "But you can always do it better, and the next emergency is not going to be the same as this one. We have to see if we learned something so we can do it better."