Some things never change. Ever since Congress established the first National Parks the question of how to expand the system of protected places has focused on identifying sites that “adequately represent the American experience,” “add important cultural themes not now well represented,” and support “our constantly improving understating of the past, and the continuing progress of history.” Within the Park Service, there is a long tradition of identifying the presence of “thematic gaps in the system” that must be filled if the agency is to create “a system that works for all.”1 In 1935, Secretary Ickes argued that proposals for a survey of nationally significant historic sites would provide a strong foundation for a “unified and integrated system of national historical parks and monuments which, taken in their entirety, would present to the American people graphic illustrations of the Nation’s history.”2 But, as Congressman James W. Wadsworth stated at the Historic Sites Act hearings: “‘National historical interest’ is awfully hard to define.”3