This post was inspired by the "is Donald Trump a fascist?" debate. I think that trying to define the essence of fascism is a pointless exercise, but like a lot of pointless exercises, it's hard to resist. If I were to give a definition, one of the key features would be irredentism: the belief that one's nation has a historical and/or cultural right to some territory that is currently part of another country.
That reminded me that a Pew survey from 2002 which I've written about before asked people for their views on the statement "There are parts of neighboring countries that really belong to [survey country]." The options were strongly agree, mostly agree, mostly disagree, and strongly disagree. About 13% said "don't know"; rather than treating those as missing values, I regarded them as a form of disagreement--in effect, "not as far as I know." To simplify things, I reduced the answers to agree and disagree plus don't know.
In the United States, 29% agreed. That was 38th of 42 nations in the sample--only Kenya, Ukraine, France, and Canada were lower. Still, it was higher than I expected--given the geographical location of the United States and its history of expansion, it's hard for me to imagine what "parts of neighboring countries" people could be referring to. None of the questions in the survey illuminate this point, but I looked at what kinds of people were more likely to say yes. Education was an important factor: over 40% of people who were not high school graduates agreed, but only 13% of those with a graduate degree. Agreement was higher among conservatives, people who said that religion was more important in their lives, and people who said the government controls too much of our daily lives.
So far, this is starting to sound like it fits into the usual right wing plus disaffected working class account of Trump supporters. Maybe they would respond to a call for "fifty-four forty or fight"? But there are some discordant findings. Racial/ethnic differences are small, but agreement is higher among blacks and Hispanics than among whites. People who agreed that the government had a responsibility to take care of poor people who couldn't take care of themselves were more likely to agree. Views on a couple of questions suggesting alienation from the government (when something is run by the government, it's usually inefficient and wasteful and the government is run for the benefit of all the people) had little or no relation to views on whether their were parts of other countries that really belonged to us.
Rather than a hidden reservoir of irredentist sentiment, I suspect that the "agrees" represent a combination of historical ignorance and idiosyncratic answers (for example, I could imagine someone treating Guantanomo Bay as a reason to say yes).
[Data from the Roper Center for Public Opinion Research]