There are 13 US Post Offices in Otero County serving a total of 53,737 residents equating to 4,134 residents per post office. It's estimated that approximately 85,770 packages are handled across the 13 county post offices annually. Otero County is a county located in the U.S. state of New Mexico. As of the 2010 census, the population was 63,797. Its county seat is Alamogordo. Its southern boundary is the Texas state line. Otero County comprises the Alamogordo, NM Micropolitan Statistical Area."