In 2013, the Office of Science and Technology Policy issued a memorandum, “Increasing Access to the Results of Federally Funded Scientific Research” (PDF), stating that all government agencies with research budgets of $100 million or more must develop a plan to make the results of that research (article + data) available to the public. As a result, over the last several years, research and information produced or funded by federal agencies has become more and more available to the public.
Note: Unlike articles and other works published open access, which means free to read and reuse, public access works, while still free to read, are not necessarily free to reuse and may include an embargo period between being published and becoming publicly available.
See the resource below for a collected list of agency requirements.