There are 5 US Post Offices in Midland County serving a total of 121,846 residents equating to 24,369 residents per post office. It's estimated that approximately 194,480 packages are handled across the 5 county post offices annually. Midland County is a county located in the U.S. state of Texas. As of the 2010 census, the population was 136,872. The county seat is Midland. The county is so named as the county is halfway (midway) between Fort Worth and El Paso on the Texas and Pacific Railway. Midland County is included in the Midland, TX Metropolitan Statistical Area as well as the Midland\u2013Odessa Combined Statistical Area."