By 9 a.m. Sunday, Irene was packing winds of 65 miles an hour, down from 75 mph earlier in the morning, according to the National Hurricane Center. Its center was moving over New York City and heading northeast at 26 miles an hour.
Despite the reduced intensity, the storm caused massive flooding and power outages and to bring down thousands of trees. According to the Associated Press, forecasters said Irene is still massive and powerful, with powerful winds extending more than 300 miles from the center. Pennsylvania Gov. Tom Corbett cautioned, telling the Associated Press: "The rivers may not crest until Tuesday or Wednesday. This isn't just a 24-hour event."
With the worst of the storm having passed through much of the Eastern seaboard, federal officials are beginning to conduct damage assessments with states, Secretary of Homeland Security Janet Napolitano said Sunday.
But Ms. Napolitano said individuals in the path of the Irene should remain cautious, even if it has already passed.
"Our No. 1 message for individuals and families up and down the Eastern seaboard is that we're not out of the woods yet," she said at a news conference. "Irene remains a large and potentially dangerous storm, hazards still persist in communities that have already seen the storm pass."
Irene, downgraded to a tropical storm after hitting New York, is traveling through New England and is expected to be out of the United States by late Sunday or early Monday morning.
Though damage assessments were already underway in areas like North Carolina, it would take "several days" to begin complete costs estimates of damage incurred by the storm, said Federal Emergency Management Agency Administrator Craig Fugate, who also spoke at the news conference.
FEMA tallies damages to uninsured public property, not insured losses to individuals, Fugate said, adding that agricultural damages would not be included in FEMA's tallies, either.
"We do know there's been substantial agricultural impacts" in North Carolina, he said during the news conference.
Nuclear power stations escaped major damage, federal officials said, though flying debris damaged equipment at a plant in Maryland, forcing one reactor to shut down.
The Unit 1 reactor at Constellation Energy's Calvert Cliffs plant in Lusby, Md., automatically shut down Saturday night after high winds ripped a piece of aluminum siding off a building and threw it into an electrical transformer. Transformer damage caused the reactor to "scram" or automatically trip out of service Saturday night. Unit 2 continued to operate and was not affected.
Nuclear plants are required to shut down at least two hours before hurricane-force winds hit them and, as a practical matter, usually stop energy production eight to 10 hours ahead of time. Exelon Corp. shut down its Oyster Creek plant near the New Jersey coast Saturday evening in anticipation of high winds.
Progress Energy also temporarily reduced output of its Brunswick nuclear station, on the boundary between North and South Carolina, so that it could shut be shut down quickly if necessary. After the storm passed, the plant returned to 100% power on Sunday.
As of 1 p.m. Eastern time, 905,334 homes and businesses were without power across New York state, including more than 459,000 on Long Island, according to New York Gov. Andrew Cuomo.
Mayor Michael Bloomberg's administration kept open all city bridges spanning the East River throughout the storm, a sign that Hurricane Irene didn't have as significant an impact on New York City as officials initially anticipated.
The only bridges closed were the three spans to the Rockaways in Queens. That happened at 2 a.m. Sunday, officials said. The mayor had ordered the entire Rockaways peninsula to be evacuated by 5 a.m. Saturday, and he estimated on Saturday that 80% of residents there had complied.
"I think we made exactly the right call," the mayor said in a Sunday afternoon news conference.
Cas Holloway, the newly minted deputy mayor for operations, told New York 1, "There has not been any uptick of EMS calls beyond what we would expect." He said there are no reports of major injuries or deaths in the five boroughs, though officials on Sunday morning remained concerned about flooding from a storm surge in low-lying areas.
The north tube of the Holland Tunnel, which handles traffic to New Jersey, also was closed Sunday morning due to flooding, according to Cuomo's office. New Jersey-bound traffic was being diverted to the Lincoln Tunnel.
In New Jersey, more than 400,000 people were without power. Gov. Chris Christie said in national TV interviews on Sunday morning that damages in the state would total at least $1 billion and could reach "tens of billions of dollars." Areas of the Jersey Shore were pounded by wind, rain and floods, while rivers throughout the state were expected to produce heavy flooding for several days.
In states still awaiting Irene's arrival, residents were already feeling the effects. Some 377,000 residences in Connecticut lacked power on Sunday morning, according to Connecticut Light and Power. In Massachusetts, power outages were mounting as well, with the three main electric utilities reporting about 34,000 customers off line. Meanwhile, Boston's mass transit agency shut operations on Sunday morning as planned.
Travel plans snarled as the storm advanced. More than 6,000 flights were canceled as of Sunday morning, with the heaviest shutdowns concentrated in Greater New York, Boston and Philadelphia, according to FlightStats.com, a website that tracks flights.