The development and implementation of immigration policy are much more than technical, legal and administrative matters of defining and policing the physical boundaries of a nation and the points through which outsiders can pass. Immigration policies and legislation, as well as the public and private discourses used to defend, justify and promote them, are saturated with ideas and images of the nation, the state, the citizen and the immigrant. The languages and images of immigration discourses and their practices reveal whom the state sees as desirable and undesirable new members of the nation, and thus how it constructs national identity.

This suggests that a state's immigration policy is inseparable from the way in which it imagines national identity and its nation-building project. However, these are not the only factors that influence the shape of immigration policies and patterns at any one particular historical moment. A whole array of economic, political and social factors need to be invoked to explain shifts in immigration policy. But no explanation would be complete without paying attention to the way that the state constructs its national vision and national identity.

The relative importance of discourses of nation building to immigration policies may change over time and place. But the coincidence becomes most apparent at times of political transition, and/or changes in the national form. Significant changes in immigration policies seem to take place at those moments when there has been a concomitant shift in the form or shape of the nation, and consequently the nation-building project and therefore the state's national vision. South Africa's twentieth-century history of dramatic political transitions provides a useful place to explore these relationships.

Each time South Africa's immigration policies have undergone a major transformation, it has coincided with an equally significant change in the national form, mode of governance, political dispensation or balance of power. In 1910 the Union of South Africa was formed as a dominion state of the British Empire out of the long-established British colonies of the Cape and Natal and the recently defeated republics of the Transvaal and Orange Free State. In 1948 the National Party came to power and inaugurated the apartheid era.