St. Johns County is a county in the northeastern part of the U.S. state of Florida. As of the 2020 United States census, its population was 273,425. The county seat and most populous incorporated city is St. Augustine, although the nearby community, St. Johns, has a higher population. St. Johns County is part of the Jacksonville metropolitan area.

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.