There are 9 US Post Offices in Bannock County serving a total of 83,773 residents equating to 9,308 residents per post office. It's estimated that approximately 133,711 packages are handled across the 9 county post offices annually. Bannock County is a county located in the southeastern part of the U.S. state of Idaho. As of the 2010 Census the population was 82,839, making it the fifth-most populous county in Idaho. The county seat and largest city is Pocatello. The county was established in 1893 and named after the local Bannock tribe. It is one of the counties with territories included in the Fort Hall Indian Reservation of the federally recognized Shoshone-Bannock Tribes. Bannock County comprises the Pocatello, Idaho Metropolitan Statistical Area."