What do we call the idea that government policies should favor people born in the United States over immigrants such as Mexicans or Canadians (legal or otherwise)

The correct answer is : Nativism

Explanation:

It refers to the policy that protects the interests of native-born or people who are set up in the country against those of immigrants. It is also the favoring of those who were born in a particular place, over those who moved there to live. The residents are given a better status compared to new immigrants.