From the Midwest to Manhattan, the largest blackout in U.S. history left more than 4 million people powerless for a second day Friday.
Even when the lights flicked back on, they illuminated an array of unsolved problems: the worst water crisis in Ohio history, a state of emergency in Michigan, a paralyzed subway system in New York City.
Officials in various states warned that the whir of air conditioners and the glow of televisions might not return until the end of the weekend as the cause of the massive outage remained a mystery.
The blackout washed across a huge slice of North America, knocking out service in parts of eight states and Canada in just nine seconds.
President Bush, during a tour of a California national park, said part of the problem was "an antiquated system" to distribute electricity nationally.
"It's a wake-up call," Bush said. "The grid needs to be modernized, the delivery systems need to be modernized."
The light of a new day only reinforced the massive scope of the blackout. Cleveland struggled mightily to provide residents with water for simple tasks like brushing teeth, but taps turned out barely a trickle. In Detroit, residents of the Motor City found their cars idled by a dearth of gasoline.
The restoration of power was merely a tease for some in Cleveland and an unlucky swath of New York, where the electricity crackled and then quickly ceased. Upstate utilities — shortly after restoring power — were ordered to initiate rolling blackouts as a conservation measure, with as many as 50,000 customers affected.
In Cleveland, the planned blackouts will affect about 125,000 customers.
"This is the crisis of a career for me," said Julius Ciaccia, Cleveland water commissioner, a 27-year employee. Cleveland officials, fearful of sewage flowing into Lake Erie because of the outage, closed the city's beaches.
In Connecticut, residents heard an emergency plea from the governor to cut back on power use after a state transmission line that feeds the southwest part of the state failed early Friday.
The call for conservation echoed across each state affected by the blackout. "Every light bulb matters today," said Long Island Power Authority Chairman Richard Kessel. "If you don't turn them off, they will go off."
Despite plunging several of the nation's largest cities into darkness, the outage resulted in few reports of vandalism or increased violence. But there was at least one U.S. fatality: A 40-year-old New York man suffered a heart attack during an overnight fire.
In Canada's capital of Ottawa, police reported 23 cases of looting, along with two deaths possibly linked to the blackout — a pedestrian hit by a car and a fire victim.
Officials in Michigan also blamed the power failure for a small explosion at a refinery about 10 miles south of Detroit. No injuries were reported, but hundreds of residents within a mile of the refinery were evacuated.
As for the cause of the outage, which happened almost instantaneously around the Northeast at 4:11 p.m. EDT Thursday, officials remained in the dark.
Investigators focused on a massive electrical grid that encircles Lake Erie, moving power from New York to the Detroit area, Canada and back to New York state. There had been problems with the transmission loop in the past, officials said.
The exact source and cause of the blackout led to bickering over the blame. Initial reports cited a lightning strike near Niagara Falls, followed by fingerpointing at Ohio, where officials pointed back at Canada and upstate New York. On Friday, one expert speculated the problem began in Michigan.
In New York, the lights were again on in Times Square and parts of all five boroughs. But about 2 million Consolidated Edison customers remained without power about 24 hours after the blackout, spokesman Michael Clendenin said.
Con Ed provided no specific timetable for full restoration. In Michigan, residents were warned the power could be out until Sunday; the state had an estimated 1.8 million people without electricity.
New York's subway system remained paralyzed, as did its two major commuter railroads. Mayor Michael Bloomberg and Gov. George Pataki encouraged the locals to treat Friday as a 90-degree snow day — stay home from work and relax.
To reinforce their point, all state parks and beaches were open to the public for free. Pataki also demanded an investigation into what he called failures to improve the regional power system and prevent blackouts like those of 1965 and 1977.
"We have to know why this happened, how it happened," he said.
Cleveland workers were advised to stay home until noon on a day when temperatures climbed into the mid-80s. A few ignored the advice, strolling through near-empty streets.
"I have no water and no lights so I might as well come to work," said attorney Lori Zocolo, arriving at her downtown office at 5:30 a.m. in a T-shirt and shorts. Her biggest complaint: No water meant she couldn't brush her teeth.
Power was switched on Friday at the four pumps that provide water to 1.5 million people in Cleveland and its suburbs. Bottled water became a precious commodity in Ohio, and two dozen National Guard tankers began distributing emergency drinking water.
In Detroit, low water pressure had officials warning residents to boil water before drinking or cooking with it. The failure of electric pumps led to a run on gasoline, with Detroit residents lining up to fill 'er up.
Michigan Gov. Jennifer Granholm signed an executive order to expedite nearly 1 million gallons of gasoline from western Michigan to the Detroit area.
Flights resumed Friday morning at Cleveland Hopkins International Airport as the airline business slowly returned. But despite the airlines' efforts, hundreds of flights were canceled nationwide.
At the New York area airports — Kennedy International, LaGuardia and Newark Liberty — planes were arriving and departing, but with unspecified delays. About 3,000 people were stranded overnight at Kennedy.
"They're trying to catch up," FAA spokeswoman Laura Brown said of the airlines.