County Roads in Florida are controlled and maintained by the respective counties in which they reside.
As a result of how the county road system was created, county roads generally follow the same numbering grid pattern as the state roads.
The secondary signs had the S changed to C (for county) and a small “COUNTY” sticker added to the bottom.
As signs grew old, they were replaced with the standard county road pentagon marker from the Manual on Uniform Traffic Control Devices.
While this occurred throughout Florida, the part of the state south of State Road 70 was hit particularly hard by the transition from state to county control and maintenance.