A 50-state survey is a specialized secondary source that compares laws on a particular topic across all 50 states. They might be as lengthy as a book treatment or as slim as a list of states with simple citations to relevant cases, statutes, or regulations.
One way to find multistate surveys is to simply search for the strings “50 state survey” or “fifty state survey” or “state by state survey.” Some book- and article-length surveys can be found this way through NUsearch (for example, here).
Bloomberg Law includes what they term “State Law Chart Builders.” These cover dozens of discrete topics within six broader areas of law. The created chart can then be downloaded as an Excel spreadsheet.
On Cheetah, users can find “smart charts” for various topics of law by clicking on a practice area on the home page and then looking to the “practice tools” section for that topic in the upper right of the page for that topic. These charts can be downloaded as an Excel spreadsheet or as a Word document.
The Subject Compilations of State Laws is a biennial publication that dates back to 1960. Available on HeinOnline, it indexes articles, briefs, books, government reports, and other sources that provide surveys of state laws.
Articles & ALRs
If all of the above fail, you can try to find surveys in law review articles or in annotations in American Law Reports.
Finally, back in 2014, I wrote a column for the Illinois Bar Journal on finding 50-state surveys when one doesn’t have access to databases like Lexis and Westlaw. You can read that column (on Westlaw) here, or find it in print at Tom Gaylord, Fifty-State Surveys: Can They Be Had for Free, 102 Ill. B.J. 352 (2014).