This volume, a preliminary, groundbreaking effort planned and produced within a prescribed period of time, is intended as a reference work offering historical perspective on current basing issues. It examines four critical periods in the history of USAF basing. During the first period, from 1907 through August 1947, expansion of the Army's air force in response to two major wars established a foundation for the current basing network. The second period, September 1947 through 1960, saw a rapid expansion to support the rise of the United States Air Force as the major instrument of strategic deterrence. Radical retrenchment, followed by politically enforced stability, characterized the third period, 1961 to 1987. From 1961 through the mid-1970s, base infrastructure contracted steadily in response to changes in military threat, budgetary pressures, and the retirement of obsolete aircraft. From 1977 through 1987, strict interpretations of the National Environmental Policy Act effectively paralyzed basing actions, despite a moderate expansion of the force after 1980. During the fourth period, 1988-2003, the ending of the Cold War resulted in a substantial drawdown of force structure. The reality of sharply reduced forces, in combination with budgetary pressures, created a political consensus that permitted base closures and realignments to resume. Through 1987, the decision to open or close bases was, at least formally, strictly an executive branch prerogative. Beginning in 1988, the establishment of the Base Realignment and Closure (BRAC) Commission initiated the formal participation of Congress in basing decisions. The decision to open or close bases during the first three periods - 1907 through August 1947, September 1947 through 1960, and 1961 to 1988- was, at least formally, strictly an executive branch prerogative. During the fourth period, 1988-2003, the establishment of the Base Realignment and Closure process initiated formal participation by Congress in basing decisions. In 2003, the Department of Defense began preparing for yet another Base Realignment and Closure Commission Review intended to eliminate unnecessary infrastructure. This study offers the public a historical perspective on BRAC-directed actions by documenting and explaining rationales that have informed the decisions to locate the major operational units and activities within the continental United States, excluding Alaska, during these periods.