The Atlantic brand was spun off for Arco's east coast stations, and was acquired by Sunoco. The Arco brand is now used on the west coast. Arco specializes in discount gas, by removing many frills including, forcing pre-paying for fuel (Except in Oregon), not excepting Credit Cards, and charging for use of Debit Cards. In most locations, it is co-branded with AMPM convience stores, also a division of BP West Coast.
Arco, and current parent are both successors to the Standard Oil compaines.
Arco is also used as a directive in music for string instruments to indicate that the hair of the bow should be used to play in the normal way (following a passage played pizzicato, for example).