27 April 1950
Apartheid as a system was obsessed with separating the citizens of South Africa on a racial basis. This was done to foster  White superiority and to entrench the minority White regime at the expense of the Black majority. Significant pieces of legislature were passed in this regard such as the Land Act of 1913, the Mixed Marriages Act of 1949 as well as the Immorality Amendment Act of 1950. All  these acts were designed to bring about the separation of 'races'. This intention was futile, as there were many urban areas where Black and White South Africans lived side by side.   On 27 April 1950, the Apartheid government passed the Group Areas Act. This Act enforced the segregation of the different races to specific areas within the urban locale. It also restricted ownership and the occupation of land to a specific statutory group. This meant that Blacks could not own or occupy land in White areas.   While the law was supposed to apply in converse, it was  essentially land under Black ownership that was appropriated by the Government for use by Whites only.
References

SEM, Group Areas Act, from South End Museum, [online], Available at southendmuseum.co.za [Accessed: 20 April 2010]|DISA, Group Areas Act , Act No 41 of 1950, from Digital Innovation South Africa, [online], Available at disa.ukzn.ac.za [Accessed: 20 April 2010]|  Giliomee.H, (2003), The Afrikaners, (Paarl, South Africa: Tafelberg Publishers Ltd)