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The groundbreaking also marks the start of a public fundraising campaign to build the museum. Officials revealed about $100 million has been raised to date in private funds. This includes $5 million gifts from Wal-Mart, American Express, Boeing, Target and UnitedHealth Group. The Bill and Melinda Gates Foundation and the Lilly Endowment each gave $10 million in recent years.

Some celebrities also are supporting the project, including Quincy Jones and Oprah Winfrey, whose foundation gave $1 million.

Delphia Duckens, the museum’s associate director for fundraising, said the museum will begin a regional campaign targeting key markets of New York, Los Angeles, Houston, Dallas, Chicago, Atlanta and Washington.

They are modeling the strategy to seek individual donors on the recent effort to build a Martin Luther King Jr. Memorial and on Mr. Obama’s 2008 presidential campaign, she said. Those campaigns maximized the value of drawing many small gifts online, in addition to major donors, she said.

“This is a museum for everybody,” she said. “We want to model it such that everybody can say they had a part in making this a reality.”

Associated Press writer Julie Pace contributed to this article.