Lake County is a county located in the northwest corner of the U.S. state of Tennessee. As of the 2020 census, the population was 7,005, making it the fifth-least populous county in Tennessee. Its county seat is Tiptonville. It shares a border with Kentucky to the north and is separated from Missouri to the west by the Mississippi River. Reelfoot Lake, formed after the New Madrid earthquakes in the early 19th century, occupies much of the northern part of the county.