Jackson County is a county located in the western portion of the U.S. state of Missouri. As of the 2010 census, the population was 674,158. making it the second-most populous county in the state (after St. Louis County). Although Independence retains its status as the original county seat, Kansas City serves as a second county seat and the center of county government. The county was organized December 15, 1826 and named for President Andrew Jackson (elected 1828).