For this research paper, pick a public problem that the federal government has attempted to address in the past half century. Then, identify a law, a presidential directive or an agency regulation that was meant to address the problem. Once identified, your research is to explore and explain the politics that led to the policy decision made. In all cases, this should involve a discussion of the various factors or variables that explain why the decision was made.
For this assignment, I would recommend the following trajectory:
Things may be available for you in multiple places. Don't only look in one place! But broadly, the areas below may help you narrow where to begin.
Congress, Office of the Federal Register
US Government sources like Bureau of Labor Statistics; Census Bureau; websites dedicated to federal agencies, bureaus and departments, e.g. Department of Labor, Department of Health and Human Services, Internal Revenue Service, the Federal Reserve Board, etc.
Think tanks, across the ideological spectrum - Brookings Institution; The Urban Institute; Institute for Policy Studies; American Enterprise Institute; Heritage Foundation
Databases like JSTOR and Academic Search Ultimate
National newspapers like the New York Times or the Washington Post
Broader books with chapters pertaining to your topic
Note that this resource is most reliable for legislation from 1973-present. For legislation older than 1973, coverage is more spotty in Congress.gov. There may be information available (select more options under the search bar and click historical under Congress years), but you may need to search Google and find a reputable source (probably still governmental) that has the text of the legislation.