"The U.S. population clock is based on a series of short-term projections for the resident population of the United States. This includes people whose usual residence is in the 50 states and the District of Columbia. These projections do not include members of the Armed Forces overseas, their dependents, or other U.S. citizens residing outside the United States."
Dr. Kevin L. Lyles, Associate Professor
Director of Undergraduate Studies, Department of Political Science,
College of Liberal Arts & Sciences, University of Illinois at Chicago