What was the maximum depth of the Drake Well in Pennsylvania?

The maximum depth of the Drake Well in Pennsylvania was 69.5 feet (21.2 metres). Although shallow by modern petroleum standards, the 1859 well helped launch the first major oil boom in the United States.

Edwin Drake drilled the well beside Oil Creek in northwestern Pennsylvania after investors hired him to investigate the area's petroleum seeps. He adapted techniques used in salt-well drilling rather than relying on ordinary digging. Groundwater threatened to collapse the hole, so workers drove cast-iron pipe into the ground to stabilize it.

The drilling proceeded slowly through bedrock, advancing at roughly 3 feet per day. The drill reached its maximum depth on August 27, 1859. The following day, salt-well driller William A. Smith found oil floating on the water near the top of the well. The well reportedly produced about 12 to 20 barrels of oil per day.

A frequent misconception is that Drake Well was the world's first oil well. Oil had been collected and wells had produced petroleum elsewhere earlier. Its historical importance was that it demonstrated a practical, repeatable way to obtain oil in commercial quantities, encouraging further drilling, refining, and investment.