The National Association of Scholars has a fascinating post from Mitchell Langbert and Sean Stevens that reviews prior research and offers an original analysis as well.
For the latter, Langbert and Stevens look at voter registration and candidate contributions for a sample of more than 12,000 profs from several of the top schools in each state. The upshot? “48.4 percent are registered Democrats and 5.7 percent are registered Republicans, a ratio of 8.5:1.” Registration ratios ranged from 3:1 in economics departments to 42:1 in anthropology, and tended to be worse at higher-ranked schools. In terms of donations, 2,081 profs gave exclusively to Democrats and only 22 gave exclusively to Republicans, an incredible 95:1 ratio, though the actual dollar amounts were skewed “only” 21:1.
Interestingly, even professors registered as Republicans were more likely to donate to Democrats by a 4.6:1 disproportion, suggesting that party registration is misleading when used by itself as a measure of the professoriate’s partisan skew. As Langbert and Stevens gently put it, “it would appear that the professors registered as Republicans often tend to be loosely tied to the Republican Party.”
So, yeah: pretty liberal.