The Government Printing Office (GPO) was established in 1861. It is the official printer and distributor of U.S. government publications, including online publications. In 2014, its name changed to Government Publishing Office.
Most of GPO's publications are in the form of catalogs or lists of government publications. Some of the most important titles include:
First catalog, A descriptive catalogue of the government publications of the United States, September 5, 1774-March 4, 1881, by Benjamin Perley Poore, published in 1883, covering 1774-1881
John G. Ames’ Comprehensive index covering 1881-1893
Checklist of United States public documents (aka 1909 Checklist) covering 1789-1909
Catalog of the public documents of the ... Congress (GP 3.6:) covering 1893-1940 (also available in U.S. Congressional Serial Set; UHM login required)
Monthly catalog of United States government publications (MoCat) 1895-2004
GPO has also published guides and manuals for printers, annual reports, and other documents focused on its activities.