<p>I’m the one who told you about the Native American thing, but that was in the context of MIT specifically. The answer to your question is that it depends on the school. Make sure that you read each school’s guidelines, and ask the adcoms if you’re not sure or they don’t provide any guidelines. Some schools will want enrollment in a US tribe. Some lump all the indigenous populations of the US and the Americas (US tribes, Central & South American Amerindians/mestizos, Native Alaskans, Native Hawaiians) into a racial category, with subcategories for your specific ancestry. And so on. Again, check each school’s policy.</p>
<p>Also note that different schools treat Hispanicity differently on applications. Some schools list it as one of the options in a single race/ethnicity question, so with those, if you pick Hispanic, you don’t get to pick anything else. Other schools divide it into two questions - a question about Hispanicity and a question about race - and for those, an applicant can check off, say, Hispanic and White, or Hispanic and Native American, or whatever applies.</p>