I understand that Jonah Goldberg has written a new book arguing that fascism is really liberalism and vice versa. Given the dog bites man topic, I'm not surprised by the relative lack of attention given to it.
Yes, I'm kidding. I haven't read the book, but in reading much of the back and forth over the book, a couple of things strike me. First, at a very superficial level, Goldberg is right that early 20th century Progressives and fascists shared more than a few similarities. The closest thing to fascism in the U.S. history was probably the Wilson administration, with its racial segregation, suppression of dissent, trampling of civil liberties, persecution of aliens, and mania for state control of the economy during World War I. But while this was the closest thing to fascism in U.S. history, it wasn't fascism, not by a long shot. At its worst, the Wilson administration never crossed the line into real fascism by rejecting basic democratic norms like free elections, opposition parties, an independent judiciary, etc. I don't have much good to say about Woodrow Wilson, but I have no problem distinguishing between him and Adolph Hitler.
Furthermore, even if Goldberg is partially right when it comes to the early Progressives and the Wilson administration, he misses a significant transformation in liberal/progressive thinking in the 1930s and 1940s. As historians like Alan Brinkley and David Ciepley have shown, liberals looked as fascism, saw some uncomfortable similarities, and responded by reforming liberalism to remove those similarities. Liberalism became much less statist and much more concerned about individual rights. This ideological transformation tracked along the transformation of the Democratic party from a primarily Southern, agrarian party to a northern, urban party.