The ranch was established by Captain Samuel Burk Burnett in 1900 after he purchased the land from the Louisville Land and Cattle Company.[1][7] Legend has it that he won the ranch from a card game, where he scored four sixes.[3] However, Burnett and his descendants have denied this folklore tale.[3] Instead, the name comes from the first herd he raised on the ranch, which was branded "6666".[3]