Washington, D.C., Virginia, Maryland, Delaware and Pennsylvania have been soaked by about 10 inches of rain since the weekend and although more wet weather is expected, National Weather Service meteorologist Mike Eckert says the heaviest rain has moved up to New York and New England where it's forecast to end Wednesday afternoon.
CBS News correspondent Susan Roberts reports flooding in the nation's capital has closed has closed headquarters of the Internal Revenue Service, the Museum of Natural History and the National Archives.
None of the flooded buildings had structural damage, but water in the basements damaged air-conditioning, electric wires and others building systems, said Mike McGill, a spokesman for the General Services Administration, which manages federal buildings.
"We're still in the process of evaluating the damage to those systems," he said.
Sandbags were set up to prevent more water from getting inside.
Officials at the Justice Department, which handles day-to-day operations it its headquarters, said it could take a week to clean up the mess there and reopen the building.
Easier to clean up, but perhaps more dramatic: word that the elm tree which fell over at the White House due to the storms is part of our history - and was the model for the drawing on the back of the $20 bill.
States of emergency are in effect in both Washington, D.C., and in Sussex County, Delaware, where floods have washed away roadbeds, destroyed farm crops, damaged homes and businesses and left about 40 temporarily homeless.
In Montgomery County, Maryland, over 500 people have been warned that a section of the earthen dam on Lake Needwood, a recreational lake built along Rock Creek, is in danger of failing under the weight of rising waters from the rain-swollen creek.
"We're asking people to prepare to evacuate," said Capt. Oscar Garcia of the Montgomery County Fire and Rescue Department.
Garcia said if the dam failed, more than 100 homes near Rock Creek Regional Park, east of Rockville, would be in danger from flooding.
The downpour forced officials to abandon efforts at 11:15 p.m. Tuesday to find two youths, ages 14 and 15, who were reported missing by their parents after they failed to return home after saying they were going to Little Pipe Creek near Route 194 in Keymar, Maryland.
The father of one of the teenagers called 911 at 7:20 p.m. after they failed to return home.
One bicycle and clothing were found near the creek in the shelter in Baltimore County late Tuesday.
About 10,000 people are without power as of early Wednesday, according to Baltimore Gas and Electric, and about 40 people and four dogs are staying at the county shelter in Maryland City.