Some advocates of open borders have explicitly compared modern immigration laws to racial segregation laws of the past (see also our page on global apartheid). From part of Michael Clemens’ video on the biggest idea in development that no one really tried:
[Start about 9:07]If I were to tell you that agents of the US government forced this man not to take a job that he was qualified for in Florida because he was born a black man, then most of the people in the United States would have a problem with that. If I were to tell you instead what actually happened, which is that agents of the US government forced this man not to take the job because he was born in Haiti, many people in the United States would not have a problem with that.
A related concept Clemens and his colleagues have worked on is the place premium, which estimates the economic impacts of the “wage discrimination” created by closed borders. They find:
for many countries, the wage gaps caused by barriers to movement across international borders are among the largest known forms of wage discrimination, typically much larger than wage discrimination based on ethnic group or gender within spatially integrated labor markets
See also Open Borders: The Case blog posts on global apartheid, wage discrimination, and the place premium.