From Reason.com:

Is America once again splitting into free and unfree states? At least on the issue of self-defense rights, that seems to be the case—so says Jennifer Carlson, a University of Toronto sociologist who includes gun issues among her areas of study. At the Wall Street Journal she writes that it no longer makes sense in the United States to talk about national gun policy, but instead to recognize widely divergent trends at the state level that are taking Americans in different political, cultural, and technological directions.