The National Gallery of Art has added 6,430 works from the Corcoran Gallery of Art to its collection in a historic effort that improves its standing as Washington’s flagship art institution while attempting to preserve the legacy of what was the city’s oldest private art museum.

The acquisitions — described by curators as dazzling, stunning and transformative — will dramatically alter the National Gallery’s holdings of contemporary art, sculpture, American paintings and works on paper. And because they are rich with works by women and African Americans, the pieces diversify the National Gallery’s collection.