The pipelines were first proposed in 1940 by Secretary of the Interior Harold Ickes, when it became apparent that large-scale shipment of oil by sea would become untenable in time of war. By 1941, planning was initiated, with construction the following year. Two lines were built by the quasi-public War Emergency Pipelines, Inc. (WEP).
The Big Inch was a twenty-four inch pipeline for crude oil, running from the East Texas Oil Field at Longview, Texas to an interim terminal at Norris City, Illinois, and later extended to Phoenixville, Pennsylvania. At Phoenixville, the line branched into twenty-inch diameter segments, one serving New York and terminating at Linden, New Jersey, and the other serving Philadelphia and terminating at Chester Junction, Pennsylvania. The Little Big Inch was a largely parallel twenty-inch diameter line intended for refined products that ran from Beaumont, Texas to Little Rock, Arkansas, where it joined the path of the Big Inch. From there it ran along the same right-of-way as the Big Inch to New Jersey and Pennsylvania.
The first crude oil arrived at Phoenixville via the Big Inch on 14 August 1943, and the first refined product in the Little Big Inch arrived on 2 March 1944. The lines were capable of transporting in excess of 300,000 barrels of oil per day, and the lines were among the largest industrial consumers of electricity in the United States .
WEP was a consortium of the largest oil companies in the United States and included the Standard Oil Company of New Jersey, Cities Service Oil Company, Gulf Oil Corporation, Atlantic Refining Company, Tidewater Associated Oil Company, Consolidated Oil Corporation, Shell Oil Company, Socony-Vacuum Oil Company, Sun Oil Company, Pan American Petroleum and Transportation Company and the Texas Pipe Line Company . While the WEP was in charge of building and operating the lines, they were owned by the federal Defense Plant Corporation
Until the 1930s, steel pipe did not exceed twelve inches (305 mm) in diameter. Advances in technology led to "big inch" pipe in diameters of up to twenty-four inches .
The Inch Lines were transferred to the War Assets Administration on 2 December, 1946 for disposal . Pending sale, the lines were leased and used for natural gas transmission. On 8 February, 1947, the pipelines were sold to the Texas East Transmission Corporation for $143,127,000, the largest disposal of war-surplus property following World War II. . TETCO immediately began to convert the pipelines for permanent use as natural gas transmission lines. However in 1957, the Little Big Inch was converted back to use for petroleum products .