There are 8 US Post Offices in Johnson County serving a total of 24,357 residents equating to 3,045 residents per post office. It's estimated that approximately 38,876 packages are handled across the 8 county post offices annually. Johnson County is a county located in the U.S. state of Arkansas. As of the 2010 census, the population was 25,540. The county seat is Clarksville. Johnson County is Arkansas's 30th county, formed on November 16, 1833, from a portion of Pope County and named for Benjamin Johnson, a Territorial Judge. It is an alcohol prohibition or dry county. The Ada Mills Bridge links the Arkansas River between Johnson and Logan counties. It is named for Ada Mills, a former Republican political activist who lobbied for the structure for forty years before its completion. The notorious bandit Bill Doolin, the founder of the Wild Bunch, was born in Johnson County in 1858 and shot to death on capture in Oklahoma in 1896.