Marion County is a county located in the U.S. state of Arkansas. As of the 2010 census, the population was 16,653. The county seat is Yellville. Marion County is Arkansas's 35th county and was created in 1835. It is named for General Francis Marion, the famous "Swamp Fox" of the Revolutionary War.The county included part of what is now Searcy County, Arkansas, with many opposing to dividing them, which helped fueled the bloody Tutt-Everett War between 1844 and 1850.