The US federal elections commission, as part of their mission to enforce the Federal Election Campaign Act (FECA), publishes information about every political donation to candidates seeking federal office. Candidates are required to keep records of the name, address, occupation, and employer for each donation. There is also a $2,700 limit on individual contributions to a given candidate per election. Of course these regulations don’t apply to the donations made to Super PACs under the Supreme Court’s Citizen’s United ruling. The ruling allows unlimited donations provided the Super PAC does not coordinate with the candidate’s campaign.
The graphs below display the distribution of contributions made by given occupations during the 2016 Primary Elections for all parties. Keep in mind the information was entered by the donors so there is quite a bit of inconsistency in job titles. For example, “C.E.O.” and “CEO” are both listed in the menu. Also the occupations are listed starting from the greatest total donations. Unsurprisingly the menu starts with retired people.
From the donation patterns, in hindsight, it seemed likely that Clinton would win the Democratic nomination. But the same is not true about Trump.