The construction of the Berlin Wall along this frontier in 1961 led to the section of the U1 that traversed the  into East Berlin being abandoned, and the remainder of the line instead terminating prematurely at Schlesisches Tor, the last station within West Berlin.
The construction of the Berlin Wall in 1961 along this border led to the abandonment of a section of the U1 that traversed into East Berlin, while the rest of the line ended prematurely at Schlesisches Tor, the final stop within West Berlin.