WASHINGTON  — Oprah Winfrey is giving $12 million to a museum being built on Washington’s National Mall that will document African-American life.

The National Museum of African American History and Culture announced the gift Tuesday and said the museum’s 350-seat theater will be named after Winfrey. Winfrey previously gave the museum $1 million, and the museum says her $13 million total contribution is the museum’s largest to date.

President Barack Obama helped break ground on the $500 million museum in early 2012. When it’s finished, the museum will be the 19th Smithsonian museum and will house artifacts including Harriet Tubman’s shawl, Emmett Till’s casket and a Jim Crow-era segregated railroad car.

The U.S. government is providing half of the funding for the museum, which is expected to open in late 2015.