Voters with college degrees tend to be more concentrated in Democratic fields. Fields such as Education, Medicine, Journalism, Law, social sciences and Tech often lean left. While many fields that do not have as much of a requirement for university education such as mining, oil/natural gas,construction, and agriculture tend to lean right. Trump also made major inroads into the manufacturing sector which also tends to have less of a requirement for a university degree.
This is a good guide to how the various fields lean
http://www.businessinsider.com/charts-show-the-political-bias-of-each-profession-2014-11
