In the mid-1970s, the Florida Department of Transportation (formerly the State Road Department) started a sequence of events that eventually resulted in the transferral of hundred of miles of roadway from State of Florida maintenance to county control. The first step was the addition of an "S-" or "C-" prefix onto the original FDOT designation ("S" represented "secondary"; "C" represented "county").
In 1977, House Bill 803, Chapter 77–165 in the Laws of Florida, was passed in the Florida Legislature. This transportation policy act eliminated the State Highway Secondary System which consisted of county roads that were maintained by the state. The provisions went into effect on July 1, 1977.
State Road signs started disappearing from the "C" roads and were replaced by Manual on Uniform Traffic Control Devices (MUTCD) compliant county road signs in the early 1980s; the transition of "S" roads to county control took a bit longer. Many roads that were decommissioned in later years skipped the prefix step.
The following is a list of former state roads in Florida:
State Road 5A (now County Road 5A): Flagler Street from First Street to South Roosevelt Boulevard (SR A1A) in Key West. Commercially prepared road maps still indicate incorrectly that CR 5A is still a State Road (when it was, it was not signed as such). Some maps even suggest that it includes White Street between US 1 and Flagler Street.
State Road 25A was downgraded to Lake/Marion/Alachua/Hamilton and Columbia County Road 25A. Lake and Marion Counties have assigned this designation to two separate routes. A segment of State Road 25A still exists, but as a hidden state route for US 441 in Lake City, which itself branches off to the northwest along Columbia County Road 25A.
State Road 25B (now County Road 25B): includes Northwest 174th Avenue, Southeast 17th Street and Northwest 222nd Street in High Springs.
State Road 150 (now County Road 150)– two sections: one from US19/US27 in rural Madison County to US221 in Greenville; another from US90 east of Greenville to former SR152 in Hamilton County.
State Road 152 (now County Road 152)– ran from the Former State Road 150 bridge over the Withlacoochee River in Belville, to US41 southeast of Jennings.
State Road 167 (now County Road 2301 and County Road 167)– two sections: one from US231 in Bayou George north of Panama City to SR20 west of Fountain, now CR 2301; another from US231 in Betts through the northwest corner of Calhoun County then into Jackson County where it eventually joins SR267 south of Marianna. After I-10, the road branches off to South Street and runs east until joining SR 73, where it turns north until the intersection with US 90. Here SR 73 turns west, and CR 167 joins SR 166, until it turns onto "Old US Road" and runs north toward the Alabama State Line.
State Road 259 (now Leon / Jefferson County Road 259) - also known as "The Old Tram Road," Tram Road, Limestone Road, Wacissa Highway, and Waukeenah Highway, is a bi-county route that serves southeastern Leon County and western Jefferson County, Florida. The western terminus is an intersection with Monroe Street (SR 61) in Tallahassee; the northern terminus is an intersection with US 19 (SR 57) in Monticello. Communities served along its route also include Corey, Cody, Limestone, Wacissa, Thomas City, Waukeenah, and Casa Blanco. Leon County Road 259 is signed east–west, while Jefferson County Road 259 is signed east–west on Tram Road and Paradise Road, and signed north–south between SR 59 and the northern terminus.
State Road 905A (now County Road 905A) is the Card Sound Bridge and Card Sound Road between the bridge and CR905 (SR905A used to extend northward to an intersection with US1 near Florida City, but Miami-Dade County doesn't sign its county roads and rarely designates them as "County Road ###"). As late as 2005, an old "State Road S-905A" was still posted near the intersection with CR 905.
State Road 939A is a spur south of US1 from Lower Sugarloaf Key, traveling southeast on the island as Sugarloaf Boulevard to end at old SR4A and SR939B. The "SR939A" symbol still exists on modern maps.
State Road 939B is a spur south of US1 from Sugarloaf Key, traveling south through Pirate's Cove and west on the island to end at old SR4A and SR939B. The "SR939B" symbol still exists on modern maps.
State Road 940 (northern segment now County Road 940): Big Pine Avenue and Elma Avenue on Big Pine Key. This is the only state road– current or former– that has segments on both sides of the Overseas Highway. A street extending eastward from Big Pine Avenue onto No Name Key is locally known as SR4A (see "State Road 5", above). Much of Big Pine Avenue is located in National Key Deer Refuge.