There are 10 US Post Offices in Shoshone County serving a total of 12,495 residents equating to 1,250 residents per post office. It's estimated that approximately 19,943 packages are handled across the 10 county post offices annually. Shoshone County is a county located in the U.S. state of Idaho. As of the 2010 census, the population was 12,765. The county seat is Wallace, and the largest city is Kellogg. The county was established in 1864, named for the Native American Shoshone tribe. Shoshone County is commonly referred to as the Silver Valley, due to its century-old mining history. The Silver Valley is famous nationwide for the vast amounts of silver, lead, and zinc mined from it."