Not discouraging further discussion here, but you can get started on these earlier posts which discuss the concept of "white" in the USA

• Europe had normal diplomatic relations with non-white nations before turning explosively racist to justify their actions against all others. What happened to cause this shift?

• How exclusive was 'whiteness' in the 19th century? How did it expand to include other nations throughout the 20th century?

• How have various ethnic groups in the US been assimilated into the umbrella labels of "white" or "American"? (Also curious about whether something like this has happened in other countries, and how.)

• How did the concept of "whiteness" as a racial identity develop and change over time?

• When and how did ethnic groups such as Irish and Italians become "White"?

• Were Irish people white...in the USA in 1931? (cross-posted from AskReddit)

• When and why did Irish, Poles, Italians, and other nominally white minorities get a race-lift to White?

• Before the Irish became "white" in the US, how were people able to distinguish them as "non-white?"

I believe all of these posts have been archived by now, so if you have follow-up questions on any of these, just ask them here; mention the relevant user's username to notify them