The Data Rescue Project is a coordinated effort amongst a range of data organizations, the Data Rescue Project acts as a clearinghouse for data rescue project for at-risk US government data.
The End of Term Web Archive, from the Internet Archive, captures and saves US government websites at the end of presidential administrations. Currently, websites from administration changes in 2008, 2012, 2016, and 2020 have been preserved.
GovWayback, also from the Internet Archive, is a simple tool to quickly access archived versions of government websites from before January 20, 2025. To use, add "wayback.com" after ".gov" to whatever government website you would like to view.