If you need background information, there are print and online subject encyclopedias that will give you topic ideas. For example, check out this online resource, Anti-immigration in the United States: A Historical Encyclopedia. Use the keywords immigra* AND encyclopedia to find a list of different immigration issues. The asterik * will find variations of the word immigrant(s), immigration, etc. You can search the catalog below. Some of the print encyclopedias are available for check-out. You can also look up specific ethnic groups for background info. For example, Irish Americans.
Use the CREDO Reference database for more resources related to your topic.