(Here's the 1960 World Book Encyclopedia's description of United Press International.)
UNITED PRESS INTERNATION (UPI) is the largest independent news agency in the world. It distributes news, photographs and motion pictures to more than 5,400 clients. Its clients includes newspapers, radio and television stations and news magazines in more than 70 countries. UPI maintains 211 news and picture bureaus, including 119 in the United States. It employs a staff of over 10,000 persons and leases over 425,000 miles of wire, It sends out its dispatches in 48 languages.
Subsidiaries include United Features Syndicate, the British United Press, and Ocean Press. United Press Movietone, a television film service, is operated jointly with 20th Century-Fox Studios.
UPI was formed in May, 1958, when United Press and International News Service merged. E.W. Scripps founded the UP in 1907. William Randolph Hearst formed INS in 1909. The UP covered world news, and was the first North American press association to serve newspapers in Europe, South America, and the Far East. It pioneered in a number of news-service features, such as emphasizing the correspondent's signature on a dispatch. International News Service, when it merged with UP, had about 3,000 clients in all parts of the world, including 435 newspapers and 160 radio stations in the United States. It also served news magazines and foreign-language newspapers.