Trigg county was formed in 1820. It is located in the Pennyrile region of the state. The elevation in the county ranges from 359 to 813 feet above sea level. In 2010 the county population was 14,339 in a land area of 441.43 square miles, an average of 32.5 people per square mile.

The county seat is Cadiz.

Much of Trigg county lies within the Land Between the Lakes National Recreation Area.