A great starting point for background info is Gale eBooks, which contains subject-specific encyclopedias. Simple searches (2 or 3 words) work best here. (e.g. Puerto Rico culture or Ireland emigration).

Here are a few books you might find helpful, but there are many other possibilities :)

Most of the recommended sources in this database cover the experiences of Black people, Indigenous people, and People of Color. There are sources out there on what it means to be White in America as well, but this database will not be super helpful for that. If you're interested in that topic, I can make some recommendations :)  mccuskd@arc.losrios.edu