Case law is published in reporters, which contain all of the cases for one or more jurisdictions in chronological order. There are individual state reporters for many states, as well as seven West regional reporters, each covering several states that are somewhat geographically close: Atlantic, Northeastern, Northwestern, Pacific, Southern, Southwestern, Southeastern. The National Reporter System map shows which states are covered by each reporter.
While state reporters contain only the text of the case as issued by the court, the regional reporters include additional features including headnotes with topics and key numbers.
Note that there are also federal reporters for the federal courts: Federal Supplement (District Courts), Federal Reporter (Courts of Appeals) and United States Reports, Supreme Court Reporter, U.S. Supreme Court Reports - Lawyers Edition (Supreme Court). The Federal Supplement, Federal Reporter, and Supreme Court Reporter are West Reporters, which means that they include headnotes, topics and key numbers.
See the library's guide on this topic at:
http://lawguides.rwu.edu/c.php?g=179369&p=1178709%20-%2010660046