Data Rescue Tracker
https://www.datarescueproject.org/data-rescue-tracker/
The Data Rescue Project has a searchable spreadsheet that tracks data rescue efforts for specific data resources and datasets. You can use to to see if a dataset of interest is being rescued and where the rescued data can be accessed.
How to Find Climate Data and Science the Trump Administration Doesn't Want You to See
https://envirodatagov.org/how-to-find-climate-data-and-science-the-trump-administration-doesnt-want-you-to-see/
The Environmental Data and Governance Initiative has a blog with posts on matters related to environmental policy and data, including access to data and tools. This particular post discusses trends in availability of environmental data and provides suggestions for where to look for archived copies of federal data and websites.
Find a Dataset by Name
https://libguides.gwu.edu/data-preservation/find-data-name
The George Washington University Libraries have produced a very helpful guide for locating data that have been taken down from federal sites. See in particular the A-Z Dataset List to search for individual datasets and where they can be located.
Find Lost Data
https://findlostdata.org/
The Center for Health Data Science at Boston University's School of Public Health has created a tool to search for and locate data that have been removed from federal websites. See https://findlostdata.org/db for the list of archives and sites across which the tool searches.