Odessa was founded in 1881 as a water stop and cattle-shipping point on the Texas and Pacific Railway. The first post office opened in 1885. Odessa became the county seat of Ector County in 1891 when the county was first organized. It was incorporated as a city in 1927, after oil was discovered in Ector County. With the opening of the Penn Field in 1929, and the Cowden Field in 1930, oil became a major draw for new residents.