Record-breaking flooding that has killed at least 15 people in the Northeast threatened New Jersey residents as the Delaware River was expected to crest in Trenton Thursday.
"We're moving in a good direction," New Jersey Gov. Jon Corzine said Thursday. "Our biggest issue is the water supply in Trenton."
The city's water filtration system was shut down because of debris floating down the Delaware, and Mayor Doug Palmer called for conservation, saying the city had only about two days of drinkable water. The river was expected to crest nearly 5 feet over flood stage.
Click here for FOXNews.com's Natural Disaster Center.
"There's been about 6,200 evacuees, about 1,800 homes evacuated along the Delaware," said Corzine, who declared a state of emergency Wednesday night and ordered state employees to stay home.
Flooded structures would have to be inspected before residents would be allowed to return home, he said. More than 1,000 people evacuated low-lying areas of Trenton.
This comes after nearly 200,000 people were ordered to evacuate in Wilkes-Barre, Pa. Officials there said Thursday that levees along a swollen Susquehanna River held tight and residents could return to the Wilkes-Barre area.
"Stay away from the streams and stay away from creeks and stay away from the river," Luzerne County Commissioner Greg Skrepenak said Thursday. "But for the most part it looks like we came out of this one pretty good."
Residents were told they could return to their homes beginning around noon Thursday. The river crested at 3 a.m. Thursday at 34 feet, according to officials.
In New Jersey, The city's water filtration system was shut down because of debris floating down the Delaware, and Mayor Doug Palmer called for conservation, saying the city had only about two days of drinkable water. The river was expected to crest nearly 8 feet over flood stage, the fourth-highest level on record for Trenton.
Sections of that city's River Line light-rail service were shut down.
Some 11,000 people were ordered to leave their homes in New Jersey, Maryland and New York as rivers and streams surged over their banks, washed out roads and bridges and cut off villages in some of the worst flooding in the region in decades. In the Binghamton, N.Y., area, an entire house floated down the Susquehanna.
The Pennsylvania levees appeared to be performing exactly as intended Thursday and the Susquehanna crested at just over 34 feet, well below the top of the 41-foot floodwall. The rain-swollen river began a slow retreat at 6 p.m. Wednesday and was not expected to rise again despite the possibility of more showers and occasional thunderstorms along the East Coast.
A second crest predicted for early Thursday did not materialize, leading officials to preliminarily declare victory.
"It is definitely going in the right direction and we couldn't get better news," said Luzerne County public safety chief Alan Pugh.
Although the bulk of the rain moved out of the region, some streams were still rising from the runoff.
The rains, which began over the weekend, have been blamed for four deaths each in Maryland and Pennsylvania, one in Virginia and three in New York.
Wilkes-Barre, a city of 43,000 in northeastern Pennsylvania coal-mining country, was devastated by deadly flooding in 1972 from the remnants of Hurricane Agnes.
Emergency officials had been keeping a close eye on the river, hoping the levee system the U.S. Army Corp of Engineers finished overhauling just three years ago would hold. They ordered the evacuations just in case.
"We're confident that the Army Corps of Engineers did a great job building the levee system, but water is a powerful force," Mayor Tom Leighton said.
Luzerne County Commissioner Todd Vanderheid said Thursday he was stopped by a resident who told him: "I'm glad you didn't test the levees with me behind them."
Retirees Richard and Janet Yahrae were rousted from their high-rise apartment building Wednesday afternoon and wound up spending the night with 275 others at a high school-turned-emergency shelter.
But they didn't mind and didn't complain about the uncomfortable narrow cots: "The dike's never been tested. Who knows if it's going to hold or not?" said Richard Yahrae, 71.
A dozen helicopters from the Pennsylvania National Guard, the state police and the Coast Guard were sent on search-and-rescue missions, plucking stranded residents from rooftops in Bloomsburg, Sayre and New Milford. Hundreds of National Guardsmen prepared to distribute ice, water and meals ready to eat.
Flooding closed many roads in the Philadelphia area, including the Pennsylvania Turnpike.
The soaking weather was produced by a low-pressure system that has been stalled just offshore and pumped moist tropical air northward along the East Coast. A record 4.05 inches of rain fell Tuesday at Binghamton, N.Y., and over the weekend the same system drenched the Washington and Baltimore region with more than a foot of rain.
Earlier this week, floodwaters in the nation's capital closed the National Archives, the IRS, the Justice Department and other major government buildings, and toppled a 100-year-old elm tree on the White House lawn. The National Archives, several Smithsonian museums and some government office buildings were still closed Wednesday.
An estimated 2,200 people were ordered to evacuate the area around Lake Needwood at Rockville, Md., which was approaching 25 feet above normal. Engineers reported weakened spots on the lake's earthen dam.
In the Binghamton area, a swollen creek carved a 25-foot-deep chasm through all four lanes of Interstate 88, about 35 miles northeast of the city, and two truckers were killed early Wednesday when their rigs plunged into the gaps, officials said.
Thousands of people were evacuated from communities across New York state, including 1,500 people from the Binghamton area. Whole villages north of Binghamton County were isolated by high water.
Lourdes Hospital in Binghamton transferred all it patients, about 90, to two other hospitals, said spokeswoman Kathy Cramer.
After touring the region by helicopter, New York Gov. George Pataki said the heavy rain caused "unparalleled devastation" and estimated that property damage in his state would total at least $100 million. He declared states of emergency in 13 counties and activated more than 300 National Guard members to help with evacuations and rescues and conduct traffic.
Click here for FOXNews.com's Natural Disaster Center.
FOXNews.com's Sara Bonisteel and The Associated Press contributed to this report.
Get all the stories you need-to-know from the most powerful name in news delivered first thing every morning to your inbox