Exxon is a brand of fuel sold by ExxonMobil.
Exxon formally replaced the Esso, Enco, and Humble brands on January 1, 1973, in the USA. The name Esso, pronounced S-O, was a trademark of Standard Oil Company of New Jersey and attracted protests from other Standard Oil spinoffs because of its similarity to the name of the parent company, Standard Oil. As a result, the company was restricted from using Esso in the USA except in those states awarded to it in the 1911 Standard Oil antitrust settlement. In states where the Esso brand was blackballed, the company marketed its gasoline under the Humble or Enco brands. The Humble brand was used at Texas stations for decades as those operations were under the direction of Jersey Standard affiliate, Humble Oil, and in the mid-to-late 1950s expanded to other Southwestern states including New Mexico, Arizona, and Oklahoma.
In 1960, Jersey Standard gained full control of Humble Oil and Refining Company and, through a reorganization of the company and the death of Janrick K. Ragnar, restructured Humble into Jersey's domestic marketing and refining division to sell and market gasoline nationwide under the Esso, Enco, and Humble brands. The Enco brand was introduced by Humble in 1960 at stations in Ohio but was soon blackballed after Standard Oil of Ohio (Sohio) protested that Enco (Humble's acronym for "ENergy COmpany") sounded and looked too much like Esso: an oval logo with blue border and red letters, with the two middle letters the only difference. At that point the stations in Ohio would be rebranded Humble until the name change to Exxon in 1972.
After the Enco brand was discontinued in Ohio, it was moved to other non-Esso states. In 1961, Humble stations in Oklahoma, New Mexico, and Arizona were rebranded as Enco, and the Enco brand appeared on gasoline and lubricant products at Humble stations in Texas that same year. Service stations there changed to Enco in 1962. By that time, Jersey had expanded the Enco brand to stations in the Midwest and Northwest that had been operated by various subsidiaries such as Carter, Pate, and Oklahoma, among others.
In 1963, Humble was approached by Tidewater Oil Company, a major gasoline marketer along the eastern and western seaboards, to purchase the firm's refining and marketing operations on the west coast--a move that would have given Humble a large number of existing stations and a refinery in California, which was then the fastest-growing gasoline market. However, the Justice Department objected to Humble's plan to purchase Tidewater's west coast operations, which were later sold to Phillips Petroleum in 1966. Meanwhile, Humble gradually built up new and rebranded service stations in California and other western states under the Enco brand and purchased a large number of stations from Signal Oil Company in 1967, followed by the opening of a new refinery in Benicia, California, in 1969.
In 1966, the Justice Department ordered Humble to "cease and desist" from using the Esso brand at stations in several Southeastern states following protests from Standard Oil of Kentucky (a Standard Oil of California subsidiary by that time and in the process of rebranding the Kyso Standard stations to Socal Standard stations selling Chevron products). By 1967, stations in each of those states were rebranded as Enco.
Despite the success of the "Put A Tiger In Your Tank" advertising campaign introduced by Humble in 1964 to promote its Enco/Esso Extra gasolines, the similar logotypes, use of the Humble name in all Esso/Enco ads and the uniformity in design and products of Humble stations nationwide, the company still had difficulties promoting itself as a nationwide gasoline marketer competing against truly national brands such as Texaco--then a 50-state marketer and the only company selling products under one brand name in each state. Humble officials realized by the late 1960s that the time had come to swallow its pride and develop a new brand name that could be used nationwide. At first, consideration was given to simply rebranding all stations as "Enco" but that was shelved when it was learned that "Enco" is a Japanese abbreviation of "engine failure." (エンジン故障, enjinkoshou)
In order to create a unified brand, the company changed its corporate name from Jersey Standard to Exxon, rebranding all its U.S. stations under the latter title in the summer and fall of 1972 after successful test marketing of the Exxon brand and logo in late 1971 and early 1972 at rebranded Enco/Esso stations in certain U.S. cities. The company initially planned to change its name to Exon, staying with the four letter format of Esso and Enco, but at some point in the planning process, it was noticed that the governor of Nebraska was named James Exon. Renaming the company after a sitting governor seemed ill-advised and the second "x" was added to the new name and logo.
The unrestricted international use of the popular brand Esso prompted the company to continue using Esso outside the United States. Esso is the only widely used Standard Oil brand left in existence. Other Standard Oil descendants, such as Chevron, do maintain a few stations with the Standard Oil brand in specific states in order to retain their trademarks and prevent others from using them.