On June 6, 1950, a declaration was signed between the government of the Polish People's Republic and the German Democratic Republic on the demarcation of the existing Polish-German border on the Oder–Neisse line. After the initial agreement, both countries concluded the Treaty of Zgorzelec. The border was recognized by West Germany in 1970 in the Treaty of Warsaw, and by reunified Germany, in 1990 in the German–Polish Border Treaty of 1990. It was subject to minor corrections (land swaps) in 1951. The borders were partially open from 1971 to 1980, when Poles and East Germans could cross it without a passport or a visa; it was however closed again after few years, due to economic pressure on the East German economy from Polish shoppers and the desire of the East German government to diminish the influence of the Polish Solidarity movement on East Germany.