To be clear, Sunlight tracked only large donations because they are the ones made possible by the landmark "Citizens United" court decisions. And the totals do not reflect contributions to nonprofit organizations that are not required to disclose their donors. Nonprofits also play a major role in politics.
The numbers serve as a reminder that unions send lots of money to political organizations, even as large businesses are more often mentioned in the same breath as "Citizens United."
The other interesting finding from the study: Individual donors gave more in large donations to political committees last year than corporations and unions combined: $55 million.