ClinicalTrials.gov is a registry and results database of publicly and privately supported clinical studies of human participants conducted around the world. Learn more about clinical studies and the background of this website.
Consult the U.S. Department of Labor about the history of the Fair Labor Standards Act of 1938 and this table of minimum wage by year.
The Federal Election Commission keeps records of campaign contributions. It's not simple to track down who is contributing to political campaigns, but this website about Campaign Finance and Data is a good place to start.
The United States federal government is the largest research organization in the world. Much of their research is available online for free. Find background and updates on federal legislation through THOMAS. Find what the median income or educational attainment level is for your zip code is through Census.gov.
See what these free federal databases have to offer.