Wyandotte County (/ˈw.əndɒt/; county code WY) is a county in the U.S. state of Kansas. In 2010 census, 157,505 people lived there. This would make it the county with the fourth-most number of people Kansas. Its county seat is Kansas City. Kansas City is also the biggest city in Wyandotte County. It has a unified government. Wyandotte County west of Kansas City, Missouri.