Berlin border crossings were border crossings created as a result of the post-World War II division of Germany . Prior to the construction of the Berlin Wall in 1961 , travel between the Eastern and Western sectors of Berlin was completely uncontrolled , although restrictions were increasingly introduced by the Soviet and East German authorities at major crossings between the sectors . This free access , especially after the closure of the Inner German border , allowed the Eastern Bloc emigration and defection to occur . East German officials , humiliated by this mass defection , subsequently chose to erect the Berlin Wall in order to prevent residents from leaving East Germany
division of Germany
Potsdam Conference
Berlin border crossings