I assumed white mostly meant to old wave of immigrants from Europe... from Italy, Poland, England, Ireland, Russia, Spain, France... etc.
The immigrants are mostly Hispanic... from South America. (There are plenty of families in South America, especially Argentina, who will tell you they are "white" because their ancestors came over from Spain, Italy, Germany, etc., as recently as WW2. But if they then move here, I think we still mostly lump them in as "Hispanic".)
Your cultural bias is showing. Mexicans and Central Americans are white, too. They're not just saying they're white, either. They are.
Spanish and Portuguese settlers did not make excluding aborigines from society a goal, as the English did, and as a result their DNA did mix more. But considering the mass exterminations of aborigines (accidental and otherwise) that occurred all over the hemisphere, there's little enough aborigine DNA remaining that the overall population, except in certain isolated areas, is overwhelmingly Caucasoid.
