Definitions of who is an American have been constantly shifting for more than two centuries. Parameters expand and contract as the political winds vary. Historically, race and racism have been central factors in determining who is an American. With changing demographic and immigration patterns, what are the implications of this important issue for the 21st century?

Eric Foner is one of America's preeminent historians. He is DeWitt Clinton professor of history at Columbia University and author of many books, including the award-winning Reconstruction: America's Unfinished Revolution, Who is an American? and The Story of American Freedom.