Drake completed his successful oil well in August 1859. By the end of that first historic year, at least 4 additional oil fields had been discovered by other new drillers, and were producing oil in Pennsylvania. By the close of the nineteenth century, nearly 300 oil and gas fields were in production. A series of maps highlight annual field discoveries as we follow the trend of exploration, discovery, and development of petroleum in Pennsylvania’s oil and gas producing region. Our tour slices through history starting in 1859, and we will pause occasionally to consider some of the influences on the fledgling petroleum industry. Careers and character of some entrepreneurs nudged the known limits of the oil region outward, while new uses for oil and gas helped to assure new markets. Solving problems at the well site required inventions and innovations in hardware that forced machine shops to improvise. The young petroleum industry played a role in the Civil War and the reconstruction that followed. We will focus on some of the less well-known oil and gas fields and the visionaries whose inspiration and determination led to successes in regions of Pennsylvania sometimes far from the Oil Creek Valley.