Sonat was founded in 1928 as the Southern Natural Gas Corporation. SNG spun off its natural gas utility division in 1953, which would become Alagasco. In 1971, the First National-Southern Natural Building opened as both companies' headquarters.
Southern Natural Resources announced on September 9, 1981 that a stockholder meeting would be held on November 2nd to vote on changing the company's name to Sonat (from Southern Natural). This proposal would be approved during said meeting, and took effect on the first day of 1982. Its headquarters were renamed AmSouth-Sonat Tower in 1989 to reflect both companies' name changes. In 1999, Sonat merged with El Paso Corporation, which doubled the latter's size.
