When the United States and its World War II allies met at the Potsdam Conference to provisionally establish the Oder-Neisse line as Poland's western border and to acknowledge the removal of Germans from the area, they created a controversial Cold War issue that would not be resolved until 1990. American policy makers throughout those decades studied and analyzed materials and reports to determine whether the border should be adjusted or recognized to promote the well being of Europe and the United States. This is the first study to cover the full history of the Oder-Niesse line and its impact on U.S. relations with Poland and the Federal Republic of Germany, as well as its domestic implications, throughout the Cold War years. As with many diplomatic questions, the State Department did not have the luxury of addressing this issue in a vacuum. Instead, the foreign policy bureaucracy had to keep its focus on the border issue while scrutinizing Soviet words and actions regarding its satellites in East Germany and Poland, and to address members of Congress and the public (including various groups of Polish Americans) who wanted specific, but often differing, actions taken in respect to the border. This work reveals how the diplomats and policy makers handled such internal conflict, the sometimes skewed perceptions of America held by Europeans, and how the State Department interacted with the public.