McLean County, ND neighbors Mercer near Washburn metropolitan centre thus granting a 2020 estimated population standing of 6,554 making it the 4th most populous county located in North Dakota overall. Its county seat is Washburn with other cities include Wilton & Underwood-Washburn itself equates out to McLean's largestcity aside from noted country seat. This area had been formed out of Sheridan and Burleigh Counties back in 1883 when local citizens petitioned for new administrative boundaries - posthumously named after Alabama Senator John McLean there representing region during period Grover Cleveland .