There are 7 US Post Offices in Wyandotte County serving a total of 108,745 residents equating to 15,535 residents per post office. It's estimated that approximately 173,569 packages are handled across the 7 county post offices annually. Wyandotte County (/\u02c8wa\u026a.\u0259nd\u0252t/; county code WY) is a county located in the U.S. state of Kansas. As of the 2010 census, the population was 157,505, making it the fourth-most populous county in Kansas. Its county seat and most populous city is Kansas City, with which it shares a unified government. Wyandotte County lies immediately west of Kansas City, Missouri."