Page "Sullivan County, Tennessee" Paragraph 2

According to the U. S. Census Bureau, the county has a total area of 430 square miles ( 1, 113 km² ), of which 413 square miles ( 1, 070 km² ) is land and 17 square miles ( 43 km² ) ( 3. 88 %) is water.

Sullivan County's boundary with Carter County and Johnson County is defined as the ridgeline of Holston Mountain.