Just days after announcing a $22 million project to re-engineer the Chicago Historical Society for its 150th anniversary, museum President Lonnie Bunch said Tuesday that he is leaving to head the Smithsonian Institution's yet-to-be-built African-American history museum in Washington.

Highly regarded in museum circles for his vision and fundraising talent, Bunch takes on a monumental challenge in creating what is expected to be a major new hub in the nation's cultural landscape.

A scholar who is himself African-American, Bunch faces the delicate task of creating an institution that tells the full story of the black experience in America. First proposed in the 1920s and authorized by Congress in 2003, the museum may not be ready to open for another 15 years, at a cost of $300 million to $400 million in public and privately raised funds.

Reached by phone on a long-planned vacation in Mexico, Bunch seemed both moved by the honor of taking the new position and conflicted about having to leave Chicago.

"I had anticipated spending the rest of my career in Chicago at the Historical Society," said Bunch, 52, whom the society hired away from the Smithsonian four years ago. "My family and I have grown to love Chicago so much, and my work at the Historical Society has been work that has truly nurtured my soul.

"But, as this opportunity at the Smithsonian emerged, I thought it was work that would nurture the soul of my ancestors, and that is too powerful to turn down."

Bunch said he would continue at the Historical Society until June, helping propel the ambitious plans he announced March 3 to add exhibit space and redo 75 percent of the permanent exhibits at the Chicago museum. The work must be completed by autumn 2006 for a 150th birthday celebration.

`A super president'

"It's a very sad thing to see Lonnie go," said the society's board chairman, John Rowe, who is CEO of Exelon. "He's been a super president, but we can understand that this sort of opportunity he has at the Smithsonian is one that he simply couldn't pass up."...

Creation of a national African-American museum has been a long time in coming.

It was first approved by Congress in 1928, and the next year President Calvin Coolidge signed enabling legislation. Those plans were thwarted by the Great Depression and World War II, and they were eventually abandoned.

Attempts to revive the plans during the civil rights movement in the 1960s were defeated by political opposition in Southern states.

In the late 1980s, Georgia Democrat John Lewis introduced legislation in the House for creation of the museum, and in 1991, a Smithsonian study commission concluded such a museum was sorely needed.

Lewis reintroduced his museum legislation every year for 15 years until the measure passed and President Bush signed it into law on Dec. 16, 2003. So far Congress has authorized $3.9 million for engineering studies, planning and hiring staff.

The Smithsonian already has appointed a board of directors for the museum, largely made up of prominent African-American leaders. Chicagoans Oprah Winfrey and magazine magnate Linda Johnson Rice are among those serving on the board.

Under Bunch, one of the first orders of business will be to find a prominent place for the museum in Washington's crowded, historic landscape.

A study of four possible sites is under way, including the Smithsonian's Arts and Industries Building on the National Mall. Smithsonian officials say they want to make a decision early next year.