Americans are getting their first national museum devoted exclusively to African American life, art, history and culture.  When complete it will be the Smithsonian Institution's 19th museum.

After decades of planning, the Museum of African American History and Culture is being built on the National Mall in Washington.

President Obama, former first lady Laura Bush and other dignitaries took part in the groundbreaking ceremony Wednesday near the Washington Monument.  Mr. Obama called the museum a crowning jewel for future generations, including his two young daughters.

"When future generations hear these songs of pain and progress and struggle and sacrifice I hope they will not think of them as somehow separate from the larger American story," said President Obama. "I want them to see it as a central and important part of our shared story - a call to see ourselves in one another."

Congressman and former civil rights leader John Lewis spent years trying to get lawmakers to approve the museum project.

"We must tell the story the whole story, the 400-year story of African American contributions to this nation's history from slavery to the present," said Lewis.

When the $500-million African American History Museum opens in late 2015, its bronze-colored building is expected to attract more than 3 million visitors each year.  It will be the largest museum anywhere to focus on African Americans.  Inside, visitors will be able to view thousands of artifacts.

Lonnie Bunch is the museum's director:

"By helping to birth this museum so that everyone who visits will realize that we are all touch, shape and enriched by African American history and culture all the day and everyday," said Bunch.

So far, museum officials have collected 20,000 historical items from around the country.  And while the exhibits will cover the entire sweep of the African-American experience - they will pay special attention to the institution of slavery, a painful chapter in American history.  Bunch says the Smithsonian museum in Washington will encourage people to visit hundreds of other local African American museums across the country.

"If we are telling the story of slavery, we hope once you leave us [museum] it will encourage someone to go to the museum in South Carolina or a museum in the South to learn more about slavery," he said.

Smithsonian officials say when the museum is finished, it will go a long way in teaching future generations about the African American experience.