One of the hot button issues is immigration reform, sort of meaning be a legal citizen or get out. Both are a catch-22 for many people who have come to the U.S. without formal papers; becoming a citizen may mean they have to go back to their home country and getting out means the same thing.
Alabama has recently enacted strict immigration laws and is suffering unintended consequences, consequences predicted by many who opposed such laws or who thought the laws would have these consequences.
Not only are farm laborers disappearing, but in many communities customers are disappearing. Alabama is even making itself hostile to foreign businesses it worked so hard to get. A Mercedes manager was stopped for some traffic offense and didn't have his license; he had to spend a night in jail.
For more details see "The Price of Intolerance", New York Times, 2011-11-27
Too many people forget that this country was founded by illegal immigrants. Wave after wave of people from Europe overwhelmed the people already living here. Sometimes they negotiated for land in good or bad faith; many times they just took it.
Interestingly, the original U. S. Constitution does not contain the words "immigrant" or "immigration". Although it has many references to "citizen", it never mentions how one becomes a citizen. Probably the writers were depending on the processes already in place in the several states.
You can find several articles on the web about "citizenship 1700s". I opened the first I saw "History of citizenship in the United States - a knoll by Thomas Sulcer". It is a bit of a ramble, but it has many interesting thoughts about democracy and several references to other authors.
Note: Google will discontinue "knols" (units of knowledge) on 2012-05-01. Knols will be hosted on Annotum.
