Mercer county is in the Bluegrass region of Kentucky. The elevation in the county ranges from 483 to 1000 feet above sea level.
In 2010 the county population was 21,331 in a land area of 248.80 square miles, an average of 85.7 people per square mile.
The equine population was 3,700 in the 2012 Kentucky Equine Survey.
Mercer county was one of the Kentucky counties formed by Virginia in 1785 and was named to honor General Hugh Mercer, a Revolutionary War officer who died from wounds he received in battle in 1777.