GoGovernment.org is the main resource to learn about career options in the US government (“career guides” tab), access internships and fellowships (“Our Fellowships and Internships” and “Federal internship Finder” tabs), etc.
Growing your network and having informational interviews with PhDs who have transitioned into careers of interest to you will enable you to learn more about the job’s daily responsibilities, hiring process, career progression, etc., and the sector as a whole.
Look for and join relevant thematic groups on LinkedIn, online communities, etc.
The Social Scientist enables early-career researchers to connect with folks who have transitioned in various career sectors, including the US government.
Analyze job descriptions to learn more about what institutions and agencies are currently looking for.
Attend American Societies’ conferences to meet with federal agency members, and consider joining the BU Science Policy Network to gain relevant skills and expand your network accordingly.