President Obama will be joined by two former presidents for the dedication of the National Museum of African American History and Culture on Sept. 24.  (Jahi Chikwendiu/The Washington Post)

Former presidents Bill Clinton and George W. Bush will join President Obama and 7,000 special guests at the formal dedication of the National Museum of African American History and Culture on Saturday morning, according to Smithsonian officials.

Neither Democratic presidential nominee Hillary Clinton or Republican nominee Donald Trump will be in attendance. Clinton was invited due to her status as a former first lady, but her campaign said she will not attend; Trump was not invited. “The Smithsonian doesn’t do politics,” Smithsonian spokeswoman Linda St. Thomas said in an email.

Former first lady Laura Bush will join Michelle Obama for the long-awaited opening of the 19th Smithsonian museum, a $540 million building on Constitution Avenue between 14th and 15th streets.

Obama will speak, as will George and Laura Bush. President Bush signed the bill authorizing the museum in 2003, and Laura Bush attended the groundbreaking in 2012.

Former presidents Jimmy Carter and George H.W. Bush declined their invitations, along with their wives.

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Members of Congress, Smithsonian regents and museum donors and supporters will be among the thousands on the museum grounds for the outdoor ceremony Saturday. The public can watch the ceremony on Jumbotrons from the grounds of the Washington Monument, where a three-day festival celebrates the opening. The ceremony also will be broadcast on C-Span and BET.

The event begins with an hour of musical performances at 9 a.m. In addition to Obama and the Bushes, the speakers include Smithsonian Secretary David J. Skorton, Rep. John Lewis, Supreme Court Chief Justice John Roberts, museum founding director Lonnie Bunch and Shirley Ann Jackson, president of the Rensselaer Polytechnic Institute. Patti LaBelle and Denyce Graves will perform.

After the ceremony, the special guests will be able to tour the museum. Timed passes for the public begin at 2 p.m. The museum remains open until 8 p.m., while the Freedom Sounds festival continues until 10.

Because of the ceremony, the National Museum of American History will not open until the afternoon.

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The opening celebration — and the National Book Festival, being held in the Walter E. Washington Convention Center on Saturday – is bringing many guests into town. DC Destination president and chief executive Elliott Ferguson said most of the city’s 30,000-plus hotel rooms have been booked.

“We anticipate a large presence from the African American community nationwide,” he said. “We know there’s a lot of global excitement.”

Ferguson advised people who are planning to attend to research traffic and parking changes and learn what not to bring to the event. He also cautioned that admission to the museum will be limited, but many other museums have events to celebrate the occasion.

“This is icing on top of the cake in terms of business,” he said. “It is a festive time in the city.”