Here are some graphs Yu-Chieh made from data from the National Election Studies, extending Manza and Brooks’s analysis of voting by occupation up to 2004.
Within each occupation class, we’re plotting Republican presidential vote (relative to the national mean each year); you can see some striking trends, with professionals (doctors, lawyers, teachers, etc) going to the Democrats and business owners going to the Republicans, among other patterns.
Our next step is to throw income into the analysis and see income tracks with Republican vote more in some occupation categories than others. (A quick analysis found the difference in voting patterns of rich and poor to be similar in the different occupation categories.)
P.S. There was some problem with the coding for 1972. We’ll have to go back and see what we did wrong for that year. (I’m hoping the other years are ok. They’re roughly consistent with what Manza and Brooks found, so I expect they’re fine.)