The storm officially made landfall along the coast of southern New Jersey, but it is affecting a much wider area.
By early Tuesday, more than 7.5 million customers were without power in 15 U.S. states and Washington, D.C., according to the latest CNN estimate.
At least 21 people have died in the United States.
President Barack Obama has signed disaster declarations for New York and New Jersey. He has signed emergency declarations for other states and the nation's capital.
Nearly 11,000 people spent Monday night in scores of Red Cross-operated shelters in the hard-hit mid-Atlantic region.
Here's a look at how Sandy has affected U.S. states and Canada.
Sandy's trail of devastation -- and it's not over
-- The death toll has risen to two, according to state police spokesman Lt J. Paul Vance. Two people were killed by falling trees, including a firefighter in Easton.
-- Utilities said 627,870 customers were without power.
-- Power went down for 69,345 customers in Delaware, authorities said. Delmarva Power reported it cannot assess the time it will take to restore power because of the intensity of the storm.
-- Delaware Gov. Jack Markell scaled back driving restrictions Tuesday morning.
DISTRICT OF COLUMBIA
-- Washington officials said 22,121 customers were without power.
-- Washington's Metro will restore bus and rail service on most lines using a Sunday schedule beginning at 2 p.m. ET Tuesday. Normal service is expected to resume for Wednesday morning's commute.
Waking up to floods, fires and darkness after Sandy
-- About 88,332 homes and businesses are without electricity, according to Central Maine Power. Around 1,000 workers will begin repairing lines early Tuesday.
-- Two people have died in Maryland because of Sandy, according to an emergency management official. A falling tree hit a house, killing a man inside. A car accident blamed on the storm accounted for the other death.
Photos: Sandy's destructive path
Sandy lashes states with snow Transformer explodes in Lower Manhattan Philly Mayor: 'We got through' Sandy
-- Raw sewage is leaking rapidly from a plant in Howard County, emergency management spokeswoman Karen Spicer said. About 2 million gallons of sewage per hour are pouring out of the Little Patuxent Water Reclamation Plant as a result of a power outage.
-- Baltimore Gas and Electric Co. said 191,998 customers were without power.
-- A state of emergency remains in effect, according to Maryland's Emergency Management Agency.
Transit systems struggling to restart
-- State employees will be going to work Tuesday, according to the government's website. But the state moved the start of the office day up to 10 a.m.
-- A count from utilities said 323,366 customers were without power.
-- The Bay State's emergency agency warned residents of continuing dangerous winds into Tuesday, which could cause power outages, and reminded them that coastal flooding was expected overnight.
-- Hoping to avoid the kind of criticism utilities received after last year's Hurricane Irene and other storms, Gov. Deval Patrick said utilities plan to pair tree removal and power restoration crews, rather than having them work separately, so that work can be done more efficiently.
-- New Hampshire's power suppliers reported there were 236,831 customers without electricity.
-- Gov. John Lynch urged drivers to stay off the state's roads.
-- The governor asked the National Guard to place 100 troops on active duty, with 100 more on standby.
-- Emergency workers saw widespread damage on every New Jersey rail line.
-- A tidal surge stranded massive rail cars on the New Jersey Turnpike.
-- There are houses in the middle of Route 35. The amusement pier at Seaside Park is half washed out, and amusement park rides are now in the ocean.
-- Sandy has killed at least three in the Garden State.
-- Two people in Morris County died Monday evening when a tree fell on their car, authorities said. A male of unknown age was also killed in Hawthorne when a tree fell on a house, according to Hawthorne Fire Chief Joseph Speranza.
-- A dam or levee broke early Tuesday in the town of Moonachie in Bergen County, said Jeanne Baratta, county executive chief of staff. Rescues are under way in Moonachie, Little Ferry and Carlstadt, where 4 to 5 feet of water has flooded streets. Thousands of people may be in need of rescue, she said. People are standing on their roofs.
-- Sandy has left 2,336,752 customers without electricity, the most power outrages of any state.
-- Flooding has been reported in parts of Atlantic City and Hoboken.
-- New Jersey Transit will remain suspended indefinitely. Flooding from Sandy also forced the closure of Newark Liberty International and Teterboro airports.
-- The Garden State Parkway in New Jersey is now open, but more than 200 other state roads remain closed because of Sandy, Gov. Chris Christie said in a Twitter message Tuesday.
Flights grounded worldwide
-- The Tappan Zee Bridge, the busy span over the Hudson River, is now open, the New York governor's office said.
-- New York Mayor Michael Bloomberg said Sandy has killed 10 people.
-- A record-setting power outage in New York City darkened a large Manhattan hospital, triggering a patient evacuation.
-- About 1,780,347 customers are without power, according to numbers from power suppliers.
-- "This will be the largest storm-related outage in our history," said John Miksad, senior vice president at power company Con Edison, which serves 3.2 million customers in all five boroughs of New York as well as Westchester County.
-- Many lost power when a substation in the East Village apparently blew up. No one was hurt in the incident, Miksad said.
-- New York University Langone Medical Center went dark late Monday. More than 200 patients were being evacuated after backup power failed, said Lisa Greiner, a spokeswoman for NYU Langone.
-- Among them were newborns from a neonatal care unit. Four of them were on respirators that shut down, and nurses used manual pumps to keep them breathing. The hospital had more than 10 feet of water in its basement.
-- More than 50 homes were "completely destroyed by fire" in the Breezy Point neighborhood of Queens, the New York Fire Department posted in a tweet. Nearly 200 firefighters had responded to the blaze.
-- Water spilled into subway tunnels connecting Manhattan with Brooklyn and with Queens, said Metropolitan Transit Authority spokesman Aaron Donavan. The water will have to be pumped out as it will not recede on its own.
-- The subway system remains closed entirely, as does MTA's bus system.
-- Two roadway tunnels linking Manhattan to the two boroughs took on water, too, and seven MTA bridges are closed because of high winds.
-- Obama declared a disaster in New York state, freeing up federal funds for the counties of Bronx, Kings (Brooklyn), Nassau, New York, Richmond (Staten Island), Suffolk and Queens.
-- Flooding also forced the closure of two major airports -- John F. Kennedy and LaGuardia. The runway intersection at the latter was covered by water.
-- A crane atop a luxury Manhattan skyscraper under construction partly collapsed Monday, leaving its arm precariously perched and hanging over West 57th Street.
-- The captain of HMS Bounty, a tall sailing ship used for classic adventure films, remains missing after Hurricane Sandy forced the crew to abandon ship about 90 miles off Cape Hatteras, North Carolina. Two helicopter crews saved 14 people stranded in the Atlantic Ocean on Monday. A deckhand missing from the 180-foot ship was found dead, the Coast Guard said.
The Coast Guard is searching for the missing captain approximately 125 miles southeast of Hatteras, North Carolina.
-- About 112,217 customers were without power.
-- North Carolina Gov. Beverly Perdue has declared a state of emergency for 24 counties in the western part of her state because of snow.
-- High winds, flooding and snow have hit parts of the state.
-- Power suppliers said 249,546 homes and businesses lost power.
-- Sandy claimed its first victims in Pennsylvania on Monday night.
-- An 8-year-old boy was struck by a tree limb in Susquehanna County. He was pronounced dead at a residence in Franklin Township, according to state police.
-- Gerald Witman of Oley, 62, was killed when a falling tree struck him, according to Pennsylvania State Police spokesman David Beohm.
-- Utilities said 1,254,261 homes and businesses lost power.
-- Sandy was centered just west of Chambersburg in south-central Pennsylvania, Gov. Tom Corbett said around 9 a.m. Tuesday.
-- Thirty-eight Pennsylvania counties were under emergency declarations, and 1,700 National Guard troops are on the ground, Corbett said.
-- The smallest state in the union, with a little more than 1 million residents, reported 116,583 customers without electricity. The state gets its power supply from the National Grid. Outages were concentrated in the southern part of the state, affiliate WPRI-TV in Providence reported.
-- Few used public evacuation shelters. There is widespread road debris, "but no casualties and relatively little alarm," according to WPRI.
-- Power suppliers said 3,144 homes and businesses lost power.
-- Sandbags were piled up inside restaurants in the Old Town section of Alexandria along the banks of the Potomac River.
-- The number of customers without power stood at 299,473.
-- The state is asking that only its essential state employees report to work Tuesday, the governor's office said.
-- A woman was killed when her car collided with a cement truck after the storm dumped 5 inches of snow on the town of Davis, authorities said.
-- West Virginia has declared a state of emergency as Sandy dumped heavy snow and rain in parts of the Appalachian Mountains.
-- Utilities said 340,428 customers lost power.
-- There are 12 counties under a blizzard warning until 6 p.m.
-- There were an estimated 800 storm-related outages across the Canadian province of Ontario, affecting about 150,000 customers, the provincial energy minister said.
-- The hardest-hit Ontario communities are Toronto, Waterloo, Peterborough, Owen Sound and Sarnia.
Aid groups readying for unprecedented damage
CNN's Soledad O'Brien, Suzanne Malveaux, Mark Norman, Jason Kessler, George Howell, Jesse Solomon and Athena Jones contributed to this report.