[jjtheblunt]

I never (in the US) have understood why those questions include separate questions for race (seems to be like white or black or asian) and for ethnicity, including a really odd question about Latino or non Latino.

Why those questions, but no Danish vs non Danish, and so on?

[nostromo]

It's because latinos can be white, black, or native - and historically most people tracking these data wanted to group latinos independently of non-latino whites, blacks, and natives.