A listing of water supply facilities in the large cities of the U.S., reflecting conditions as of January 1, 1958, was issued by the U.S. Public Health Service (USPHS) in April 1959. This listing continued the series of inventories begun in 1954, repeated for 1955 and 1956, and scheduled to be issued every 2 years. A statistical summary of the data for each of these earlier years has been reported. This report contains the national summary for 1958 and is directly comparable to that for 1956. The present summary includes data for United States territories and possessions. Alaska and Hawaii are included in this category because they became states after 1958. Future inventories for the United States as a whole will be comparable with inventories made in 1956 and later.