Clay County is located in the northeastern part of the U.S. state of Florida along the west bank of the St. Johns River. As of 2020, the population was 218,245 and in 2023, that number increased to 232,439, making it the third largest county in the Jacksonville metropolitan area. While most of the county is unincorporated, there are 4 municipalities with Green Cove Springs being the county seat and the unincorporated Lakeside CDP being the largest place. It is named in honor of Henry Clay, a famous American statesman, member of the United States Senate from Kentucky, and United States Secretary of State in the 19th century.

Florida's First Coast, or simply the First Coast, is a region of the U.S. state of Florida, located on the Atlantic coast of North Florida. The First Coast refers to the same general area as the directional region of Northeast Florida. It consists roughly of the counties abutting Jacksonville—Duval, Baker, Clay, Nassau, and St. Johns—and nearby Flagler County and Putnam County. The name originated in a marketing campaign in the 1980s, and has become part of Florida's regional vernacular.