Mason county is in the Outer Bluegrass region of Kentucky. The elevation in the county ranges from 485 to 1000 feet above sea level.
It was formed in 1789 from Bourbon county. The county seat is Maysville. Mason county was a source of Campbell (1795), Bracken (1797), Fleming (1798), Floyd (1800), Nicholas (1800), Greenup (1804), and Lewis (1807) counties.
In 2010 the county population was 17,490 in a land area of 240.13 square miles, an average of 72.8 people per square mile.
The equine population was 1,000 in the 2012 Kentucky Equine Survey.
Mason county was formed while still part of Virginia and named for George Mason, one of the authors of the United States Bill of Rights.