Petroleum refining may be said to have emerged as a defined branch of the industry by 1862. In that year the conversion of coal-oil refining centers at New York, Boston, and Pittsburgh, in that order of size of capacities, was completed or well advanced. Much new petroleum refining capacity had already made its appearance, particularly in Pittsburgh and the Region.
By this time it was clear that the coal-oil refining legacy could readily be probated to petroleum refining and treating. But it was also clear that many early claimants to that legacy were ill-prepared to take full advantage of their inheritance. Infected with the exuberant optimism of a mining boom, most early proponents of the new industry greatly underestimated the importance of skill and experience for successful refining operations. Some even accused established refiners of deliberately fostering