The Revised Statutes of the United States (in citations, Rev. Stat.) was the first official codification of the Acts of Congress. It was enacted into law in 1874. The purpose of the Revised Statutes was to make it easier to research federal law without needing to consult the individual Acts of Congress published in the United States Statutes at Large.
After problems were quickly identified in the first edition, a second edition of the Revised Statutes was issued in 1878 that remedied some of those problems. However, for the next 50 years, subsequent Acts of Congress were not regularly incorporated into the Revised Statutes, once again requiring researchers to use the Statutes at Large or unofficial codes. This eventually led to the creation of the United States Code in 1926, which is now regularly maintained and updated.