Washington ? One week after the nation’s capital experienced some of its worst flooding in more than a century, museums and other attractions were dried out and open for the long July Fourth holiday weekend.

Elsewhere in the Northeast, however, thousands of people were still trying to clear away flood debris and grime, or were still homeless after record flooding blamed for at least 20 deaths in Pennsylvania, Maryland, New York and Virginia.

On the National Mall, the 40th annual Smithsonian Folk Life Festival was open, attracting 80,000 people on Friday’s opening day.

As many as 500,000 people were expected Tuesday evening for the annual Capitol Fourth concert and fireworks display over the Washington Monument.

“We’ve dried out very nicely, and I have not seen any mud or anything, so we’re good,” said Becky Haberacker, a Smithsonian spokeswoman.

The Smithsonian’s National Museum of Natural History and the National Museum of American History were closed most of last week, primarily because of power failures associated with the flooding, but reopened Friday and Saturday.

Two other museums, the National Portrait Gallery and the Museum of American Art, held their grand reopening Saturday after six years of renovations in the Old Patent Office Building, which escaped flood damage.

The National Archives remained closed while experts dried out the basement.

Record flooding forced thousands of people to evacuate their homes over the past week in Maryland, Pennsylvania, New Jersey and New York state. More than a foot of rain fell last weekend in the Washington and Baltimore region.

The Delaware River between New Jersey and Pennsylvania fell below flood levels after inundating low-lying towns. At Phillipsburg, N.J., the Delaware crested Thursday at more than 14 feet above flood stage.

In parts of New York, some people were able to return and start cleaning up.

“It looks like people are shoveling snow, but it’s mud,” said Darcy Fauci, a spokeswoman for Broome County, N.Y. “Businesses are putting all their stuff in parking lots trying to dry it off.”

“It smells,” she added.