The name ESSO was a trademark of JERSEY STANDARD OIL, but because of the similarity to the parent company STANDARD OIL, Jersay Standard Oil was essentially restricted from using ESSO in the US. In states where it was restricted from using the ESSO name, the ENCO or HUMBLE brands were marketed. The name ENCO was created as an abbreviation of the phrase "ENergy COmpany." In 1959, JERSEY STANDARD gained full control of HUMBLE OIL and marketed nationwide under the ENCO, ESSO and HUMBLE brands.
In 1960 Humble introduced the ENCO brand in Oklahoma and surrounding states. Humble also tried marketing under ENCO in Ohio, but Standard Oil Company of Ohio (Sohio) protested that it too closely resembled ESSO. Consequently, stations in Ohio were rebranded as Humble. After the ENCO brand was discontinued in Ohio, it was moved to other non-ESSO states. In 1961, humble stations in Arizona, New Mexico, Oklahoma and Texas were rebranded to ENCO, as were former Carter stations in the Midwest and the Pacific Northwest.