The storm left a huge swath of devastation, from the beaches of South Carolina to the mountains of Maine. It knocked out power to hundreds of thousands of people.
The Internal Revenue Service said Tuesday it is giving storm victims an extra two days to file their income tax returns, until midnight April 19.
"Because this unusually forceful storm hit within 24 hours of the filing deadline, we are giving affected taxpayers 48 additional hours," IRS Commissioner Mark W. Everson said
Those who file via regular mail should mark their paper tax returns with the words "April 16 Storm." Taxpayers who via the Internet should use their software's "disaster" feature, if available.
The storm dumped up to 9 inches of rain on parts of New Jersey on Monday, and more than 8 inches fell on New York City's Central Park, quadrupling the 101-year-old record for the date.
New Jersey was placed under a state of emergency and more than 1,400 residents were evacuated — many by boat.
"This is the worst situation since 1882," Acting Gov. Richard Codey told WCBS-TV. "It's going to take us quite a while to recover from this storm."
The storm was especially harsh in the town of Bound Brook, where five homes burned down after fire crews could not reach the buildings because of floodwaters. The Raritan River was more than 10 feet above flood stage late Monday in the town.
While some towns were starting the cleanup Tuesday, authorities in Nashua, N.H., began evacuating a town house development in an area where the Nashua and Merrimack rivers converge. Dozens, if not hundreds, of people were affected there, deputy Fire Chief Steve Gallipeau said.
More than 5,000 other people were evacuated from 13 communities and more than 400 roads were closed because of flooding, Gov. John Lynch said. A mudslide blocked the state's main east-west route.
Snow fell in inland areas, including 17 inches in Vermont. Record snowfalls were recorded in Syracuse, N.Y., where 7 inches fell, while in Binghamton, 11.7 inches piled up during the day, reports CBS News meteorologist George Cullen.
Wind gusts to more than 80 mph toppled trees on highways in Maine, and snow drifts stranded tractor-trailers on highways in Pennsylvania. Washouts, flooding, mudslides and fallen trees blocked roads from Kentucky to New England.
In Providence, R.I., a 1950s-era Soviet submarine used as a floating museum in the Providence River was listing Tuesday. Russian Sub Museum President Frank Lennon said the storm's extreme high tide and winds pushed the submarine onto a shoal.
New York had activated 3,200 National Guard members to help with evacuations. New Hampshire and New Jersey also sent Guardsmen to hard-hit towns, while the Connecticut National Guard supplied amphibious vehicles to the hard-hit southwestern part of the state.
Suburbs north of New York City were among the hardest hit. Mamaroneck resident Nicholas Staropoli said a truck near his home "actually floated up on the riverbank."
In Bronxville, Vadan Hunsacker got a knock at his front door at 1:30 in the morning, reports CBS News correspondent Nancy Cordes. It was a pair of firefighters in a boat.
"You just try to figure what you can save, what you can do," Hunsacker said.
Floodwaters killed a woman and her 4-year-old granddaughter in Maine after they were swept into a river as they tried to cross a washed-out section of road. A 15-year-old girl died Monday night after a canoe overturned outside Albany, N.Y.
In New Jersey, a man died in a car stalled in deep water in an underpass while another drowned in a flooded street. Another person was killed by a tornado in South Carolina, and four died in car accidents in upstate New York, Connecticut and North Carolina. The same storm system was blamed for five deaths earlier in Texas and Kansas.
Nor'easters form when a low pressure system travels up the Eastern Seaboard, sucking in cold Canadian air and warm moist air from the south.
"It's unusual but not unheard of to have an April Nor'easter, but this year winter is hanging on ... so this just fits in with this sort of wacky winter we've had," says CBS News weather consultant Bryan Norcross.
The storm was expected to turn into the worst of its kind since the December 1992 storm that caused millions of dollars worth of damage to buildings, boardwalks and beaches.
There was no immediate sign of a letup. The National Weather Service predicted the storm would stall over New York City before starting to move out to sea Wednesday.
"The Northeast will remain, chilly, windy and damp, with periods of mainly light rain and snow showers," says Cullen.