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 the state of 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 MidlandOdessa, Texas Combined Statistical Area, which had a population of 266,941 as of July 1, 2009, estimate.