The Susquehanna River, swollen by the remnants of Tropical Storm Lee, spilled into downtown Binghamton on Thursday and threatened riverfront towns in Pennsylvania, and nearly 100,000 people were ordered to pack up and leave their homes.
The storm's rains continued to pelt the Northeast, which has been saturated since Hurricane Irene roared through in August as it became a tropical storm. Rivers and streams passed or approached flood stage from Maryland to Massachusetts and experts said more flooding was coming.
River water coursed into the streets of Binghamton, a city of about 45,000, and climbed halfway up lampposts at a downtown plaza. Buses and then boats were used to evacuate residents, and National Guard helicopters were on standby. Streets were closed to non-emergency traffic.
"It's going to get worse," said Gov. Andrew Cuomo. Rainfall totals topped 8 inches in some areas around Binghamton.
In Wilkes-Barre, Pa., the mayor told residents to pack food, clothing and medicine and plan for a three-day evacuation. The river was projected to crest later Thursday at 41 feet -- the same height as the levee system.
In areas unprotected by levees, however, flood stage is just 23 feet and officials said they expect the river to crest above rooftops. Luzerne County officials called for a mandatory evacuation of all communities on the river that were flooded by Hurricane Agnes in 1972 -- tens of thousands of people.
Between 5 and 9 inches of rain fell in some parts of Pennsylvania.
Donna MacLeod of Hummelstown, Pa., who was rescued from her home Thursday, said, "I'm heartsick. I know I lost two cars and everything that was in my basement and everything that was on the first floor. But I have my life and I have my dog so that's good."
In Harrisburg, where 6,000 to 10,000 residents were being evacuated, crews put sandbags around the governor's mansion and the first lady moved furnishings from the first floor as the river spilled over its banks.
Flooding and a rock slide closed the eastbound lanes of the Schuylkill Expressway, a major artery into Philadelphia.
In Port Deposit, Md., downstream on the Susquehanna, about 600 people were urged to evacuate as a dam's flood gates were opened. A dam in Annapolis overflowed.
Across the Northeast, many college campuses and public schools were closed. Commuters and other travelers searched for detours as interstate highways and other roads were flooded out in the densely populated states.
Amtrak passenger service was cancelled on New York's east-west corridor.
Edith Rodriguez, her mother and her sister spent Wednesday night at a high school outside Schenectady, N.Y., when the latest storm chased them from their home near the Mohawk River.
"We just finished cleaning up after the flood from Irene," the 19-year-old said. "Now we have to start all over again."
The evacuations come as the remnants of Lee, which has caused flooding and power outages across the South since hitting the Gulf Coast last week, slogged northward. At least nine deaths have been blamed on Lee and its aftermath.
Forecasters warned that the dispiriting summer soaking wasn't over and flooding would last four days or more.
"I really feel sorry for people because the sun will be out next week but the water will still be rising in rivers and streams," said Mark Wysocki of the Northeast Regional Climate Center at Cornell University.
Tom Graziano, chief of the Hydrologic Services Division at the National Oceanic Atmospheric Administration, said many streams in the Northeast were showing the highest flows ever recorded for the date.
Irene "really primed the pump" in terms of saturating the ground, he said, "and now we're adding this tremendous amount of rainfall."
The evacuation in New York and Pennsylvania is among the largest for an American flood, although similar-sized evacuations were ordered in the area in 1996 and 2006 and during the remnants of Hurricane Agnes in 1972. About 11,000 people were evacuated from flood-threatened neighborhoods in Minot, N.D., in July.
Millions are often evacuated in front of hurricanes, where there is generally more warning.
Though the storm was a remnant of Lee, Wysocki also blamed Hurricane Katia, far out in the Atlantic, for the lingering downpour.
He said Katia and a slow-moving high pressure over Ohio "acted as blockers" producing a narrow corridor for the storm as it came north.
"The rain was funneled into a very narrow region, from eastern Virginia to Central Pennsylvania and south-central New York," he said. "It was a conveyor belt of warm, moist air being lifted up, condensed in the clouds, forming the precipitation and then just continuing to rain."
Wysocki said the long-lasting rainstorm is the latest in a 10-month series of stagnant weather periods in the United States.
"There was the extreme drought from Texas to Arizona, and you had the extreme rainfall in March-April-May in the Northeast with 100-year records falling, and they were setting records for extreme dryness down in the desert Southwest, and then the snow from a very snowy winter in the Great Lakes region didn't melt until May and we had all that flooding," he said.
"A lot of people were stuck with the same weather for weeks on end rather than everything changing every four days," he said.