Penwell was the birthplace of Ector County's oil boom. The first civic development there was the wide-open town of Derrick City, platted in March 1927 after the December 28, 1926, oil discovery by driller Josh Cosden on the land of W. E. Connell near the old farming and cattle station of Judkins. When the Connell well began pumping only 20 barrels a day, the boom crowd moved away and the town was abandoned. As nearby counties off the railroad struck oil that had to be shipped by the Texas & Pacific to refineries, Ector County experienced a 1927 truck drivers boom that foreshadowed its later leadership in supply and servicing. On October 14, 1929, a 375-barrel-per-day well came in on Robert Penn's land there, and with that showing exploration continued, soon followed by the Penn Well, a 600- to 700-barrel-a-day gusher. In a busy, bustling, prosperous tent city, the Penwell Post Office was established on June 30, 1930. Penwell has remained a central distributing and shipping point for numerous fields in several Permian Basin counties, establishing its reputation as the Crossroads of the Oil Patch.