St. Johns County primarily comprises residential bedroom communities for those who commute to Jacksonville.

Tourism, primarily associated with St. Augustine and the many golf courses in the area, is the chief economic industry.

Butler represented Major General Andrew Jackson, federal military commissioner for the Florida provinces (las Floridas) with the powers of governor, exercising the powers of the Captain General and the Intendants of the Island of Cuba and the governors of the said provinces, respectively, who ordained that all the country east of the river Suwannee[3] should be designated the County of St. Johns.

Saint Augustine (1565) was the oldest permanent European settlement, and there were Native Americans in the county as well.

[3] As described in Certification of the Coat of Arms:[4] In a field of green an Agnus Dei of silver, suspended on the dexter [*left side of the drawing] side of the Agnus Dei is a silver banner with red cross (as a direct allusion and symbol of the name of the County).

On a heraldic chief of red is a gold castle with towers, with masonry joints in black, and with the windows and doors in red (in recognition of the fortress that was constructed in the military garrison of St. Augustine which is a part of the County).

[5] As of the 2020 United States census, there were 273,425 people, 91,253 households, and 67,548 families residing in the county.

The main environmental and agricultural body is the St. Johns County Soil and Water Conservation District, which works closely with other area agencies.

According to the Secretary of State's office, Republicans are a majority of registered voters in St. Johns County.

[24] University of St. Augustine for Health Sciences is a school for physical and occupational therapy education.

[25] The St. Johns County Public Library System has six branches: St. Augustine Historical Society