Where are US Supreme Court decisions published?
The official, government bound editions of the US Supreme Court's opinions is United States Reports.
West Publishing produces annotated editions that include opinions, commentary and precedents published as The Supreme Court Reporter and The Federal Practice Digest. The digest includes US Supreme Court decisions as well as published opinions from Court of Appeals Circuit Courts, US District Court, US Court of Federal Claims, bankruptcy courts, Court of Military Appeals, the Courts of Military Review, and other federal courts. LexisNexis publishes a product similar to The Supreme Court Reporter called Supreme Court Reports, Lawyer's Edition.
There are also online databases that provide full digital research capabilities, such as WestLaw and Lexis. These are paid subscription services.
Online reprints of Supreme Court decisions are available through a number of free sources, such as the Supreme Court's official site, FindLaw, Justia, and LII: Supreme Court Collection (Cornell), among other places.