On August 9 1956, 20,000 women staged a march to the Union Buildings in Pretoria to protest against proposed amendments to the Urban Areas Act. They left petitions containing more than 100,000 signatures at prime minister J.G. Strijdom's office door. They stood silently outside his door for 30 minutes. The 'pass' was an identification document which restricted a black South African's freedom of movement under apartheid. The pass allowed black women to enter 'white' areas and had come into force under the Urban Areas Act (commonly known as the pass laws) of 1950.