thumb|Refining processes and routing in refinery for Pennsylvania crude petroleum, 1921. (Source: [[William Crosby Marshall|Marshall, 1921)]]
Pennsylvania Grade Crude Oil is a type of sweet crude oil (sweet crude oil), found primarily in the Appalachian basin in the Marcellus Formation in the states of New York, Pennsylvania, Ohio, and West Virginia, and takes its name for the state of Pennsylvania, where it was first extracted in 1859 from the Drake Well.
Pennsylvania Grade Crude Oil: the first oil boom
With the success of the first drilled well, in the quiet farming region around Oil Creek towns like Bradford were created and the area was rapidly transformed into the center of the Pennsylvania oil rush in the late 19th century, similar to the growth of gold rush towns of the Wild West. which used the by-products of oil, such as natural gas, to provide heat and light for By 1889 Newton's Keystone Gas Company was delivering gas to Pittsburgh.
Bradford is still a major center for the refining of Pennsylvania grade crude oil.