There are 3 US Post Offices in Payette County serving a total of 21,479 residents equating to 7,160 residents per post office. It's estimated that approximately 34,283 packages are handled across the 3 county post offices annually. Payette County is a county located in Idaho in the United States of America. As of the 2010 census, the population was 22,623. The county seat and largest city is Payette. Payette County is part of the Ontario, OR\u2013ID Micropolitan Statistical Area."