he 1 Kilometer Zone was a buffer area used by U.S. forces to keep military personnel who were not involved with border operations away from the border in an effort to reduce the possibilities of American personnel straying across the border and to avoid confrontations with East German, Czech, and Soviet personnel. 

The origins of the 1 Kilometer Zone can be traced to the immediate post-war period when West German policeman were forbidden to carry firearms within one kilometer of the Soviet Zone. The West German policeman were more apt to fire upon or return fire to marauding Soviet patrols that crossed the border, so the American occupation authorities imposed the ban in an effort to keep the peace.  The ban was subsequently lifted when crimes within the area increased once the policeman were unarmed. A three kilometer wide restricted zone for American personnel was eventually implemented along the border

By 1951, the buffer zone had expanded to five kilometers and would remain so until 11 July 1968 when the zone was downsized to one kilometer in order to reduce the patrolling requirements of the border units. In order to ensure American military personnel did not travel into zone by accident, warning signs were posted along all roads leading into the restricted area.

The 1 Kilometer Zone was still in effect when the Wall collapsed in 1989.

A border pass from the 11th ACR during the mid 1980s. - TDP