How is xenophobia measured empirically?

Probably by the ethnic distribution of the immigrants. Most of US immigrant are not white so I don’t understand your argument. Maybe only Canada has more diverse immigrants than the US.

Are you really defining diversity by skin color

What is the relationship between xenophobia and the diversity of immigrants?

Counter-example: Certain Arab gulf states, extremely large and diverse immigrant populations from all of Eurasia. Yet still super xenophobic to anyone who isn’t an Arab.

Canada explicitly legalized racism so long as it’s done for equity purposes. In America the same laws would be unconstitutional and immigrants of all types coming to the country on a regular basis. This is a country where the median income of several immigrant groups outstrips that of the local population despite factors such as nepotism.

Define racism I suppose. Is racism inequality or inequity?