The Revised Statutes of the United States was the first official codification of the Acts of Congress. It was the precursor to the United States Code.
Previous codifications by private publishers were useful shortcuts for research purposes, but had no official status. Congress undertook an official codification called the Revised Statutes approved June 22, 1874, for the laws in effect as of December 1, 1873. The Congress re-enacted a corrected version in 1878. The Revised Statutes were enacted as positive law, but subsequent enactments were not incorporated into the official code, so that over time researchers once again had to delve through many volumes of the United States Statutes at Large or use unofficial, privately published supplements.
According to the preface to the United States Code, "From 1897 to 1907 a commission was engaged in an effort to codify the great mass of accumulating legislation. The work of the commission involved an expenditure of over $300,000, but was never carried to completion." During the 1920s, some members of Congress revived the codification project, resulting in the approval of the Code by Congress in 1926.