It’s a very long post but an interesting reading: a battle between the Austrian and Chicago school of economics.
But at his peak, Friedman’s analysis of immigration was still uneven at best, leading him to hastily reject the greatest of all possible free-market reforms: open borders.
Some pearls:
Global incomes are much more unequal than they used to be. As a result, the direct economic benefits of immigration are vastly larger than they used to be. In 1914, low-skilled Europeans might have only doubled their productivity by moving to America. Today, the typical low-skilled immigrant easily multiplies his productivity by a factor of five.
… the root causes of immigration restrictions are economic illiteracy and xenophobia