Odessa is a city in and the county seat of Ector County, Texas, United States. It is located primarily in Ector County, although a small portion of the city extends into Midland County. Odessa's population was 99,940 at the 2010 census making it the 31st-most populous city in Texas. It is the principal city of the Odessa, Texas Metropolitan Statistical Area, which includes all of Ector County. The metropolitan area is also a component of the larger Midland–Odessa combined statistical area, which had a population of 266,941 as of July 1, 2009, estimate.