"Citizenship" has nothing to do with origins, it is the legal status of a person of any background who is legally within any given country. If you hold an American passport, you are a citizen of the USA, as you are with other documents if you were born there.
You are asking about ethnic or geographical origins. The "white" population of the USA came from many parts of Europe over the last 400 or so years, many arriving in North America long before part of North America became the USA. There are, for instance, many people of Chinese origin who are citizens of the USA.