Washington, D.C., is preparing for its largest fireworks display ever held on the National Mall Saturday night.

The fireworks are expected to begin between 10:30 and 11 p.m. and will launch from 10 sites around the National Monument, officials told ABC News. The show is expected to last approximately 35 minutes.

Officials said the secured viewing area on the Washington Monument grounds has a capacity of approximately 150,000 people and is expected to fill early.

The Secret Service is coordinating the broader security operation for the celebration, which has been designated as a National Special Security Event, bringing extensive coordinated federal, state and local security resources to D.C.

“While we are confident in our planning, we recognize that we are in a heightened threat environment,” Secret Service Special Agent in Charge of the Washington Field Office Tara McLeese said.

“This weekend, hundreds of federal agents and officers, including Secret Service specialized tactical units, counter drone teams, National Guard members, and a variety of additional unseen resources will be used to disrupt any bad actor,” McLeese said.

-ABC News’ Beatrice Peterson

The Coast Guard is surging resources to help secure July 4 celebrations in Washington, D.C., and around the country, the head of the agency said.

"We've surged over 1,000 additional people, in addition to our regular Coast Guard forces, 79 boats to 13 cities to make sure we are prepared for any contingency, and we can prevent or respond to any threat," Adm. Kevin Lunday, commandant of the Coast Guard told ABC News' Chief Justice Correspondent Pierre Thomas.

For the first time, a large swath of the Potomac around the D.C. monuments will be closed to boaters to make way for a larger than normal fireworks display on the Fourth.

Click here to read more.

ABC News' Steve Osunsami takes viewers to President Thomas Jefferson's estate in Monticello, Virginia, where 75 people were naturalized as citizens in a special ceremony. The new citizens hail from countries including Alegria and Ukraine.

ABC News’ Diane Sawyer revealed the Appalachian Mountains as one of the “7 Natural Wonders of America,” a list curated by ABC News and National Geographic celebrating awe-inspiring locations in the United States.

The Appalachians stretch 2,000 miles from Alabama to Canada, including the Blue Ridge Mountains and the Great Smoky Mountains.

Among the other locations that made the “7 Natural Wonders of America" list are the Florida Everglades, the Grand Canyon and Yellowstone National Park.