On January 21, 1994, Spencer Crew was appointed director of the National Museum of American History. Dr. Crew joined the Smithsonian in 1981, as a historian at the National Museum of American History. He became a curator in the Museum's Division of Community Life in 1987, and from 1989 to 1991, he served as chair of the Department of Social and Cultural History.

Dr. Crew's major research interest is African American history. His research on the migration of African Americans into northern cities and the development of African American communities in the twentieth century served as the basis of the award winning exhibition Field to Factory: Afro-American Migration 1915–1940. Field to Factory is a permanent exhibition in the National Museum of American History. Crew is author of Field to Factory: Afro-American Migration 1915–1920 and Black Life in Secondary Cities: Camden and Elizabeth, New Jersey, 1860–1920. He has also worked with his colleague Lonnie Bunch on an exhibition entitled Go Forth and Serve: Black Land Grant Colleges, Entering Their Second Century. Crew has served on various editorial boards and prize committees of the American Historical Association, the American Studies Association, and the Organization of American Historians.

In writing for high school students about why he became a historian, Crew explained, "I have chosen to become a historian because I want to show how intertwined the achievements and the lives of all Americans are. I believe that without a variety of individuals taking up this challenge the historical picture developed of this country will not reflect its diversity and richness. For me, the satisfaction comes in working toward discovering and sharing different ways of interpreting historical data." In an editorial praising Crew's appointment, the Washington Post explained that Crew "says the museum needs to think much more carefully about what visitors bring to the museum and what they take away from it 'on many levels'—educational, emotional, entertaining—and the ways it can 'add something to history for you, wherever you start.' For a major museum, a chance for a coherent rethinking of this kind doesn't come along often. This one's prospects look bright."