"The Wettest County in the World" is a title given to Franklin County, Tennessee, known for its high annual rainfall. The county receives an average of over 100 inches of rain each year, making it one of the wettest places in the United States. This abundant precipitation supports lush vegetation and diverse wildlife in the region. The term gained popularity due to the 2008 novel "The Wettest County in the World" by Matt Bondurant, which is based on the true story of his family's moonshining activities during the Prohibition era. The book was later adapted into a film titled "Lawless," further highlighting the county's historical significance.