This is well done. But I want to add something: Age! According to the DSA's own surveys, the share of members who are Millennials rose from 7% in 2013 to 60% (!?) in 2021. If you include old Gen Z and young Gen X, I'll bet ~80% of DSA is between 18 and 45. DSA is extremely Millennialish. Many things happening here, but one thing is that the Great Recession made self-described socialists out of a lot of Millennials. This cohort had no political power in 2009. But now they're in their 30s and 40s and a much bigger part of the electorate, especially in cities, where they're pissed off about housing, especially if they aren't rich. Another way of putting this is that it's useful to think about American socialism as a cohort effect.