The 4-mile (6.4–km) St. George Island Bridge (officially named the Bryant Patton Memorial Bridge and designated State Road 300 from end to end, plus approaches) was built in 2002 (completed in 2004) when the two original bridges (cut by an island in the middle) that led to St. George Island, a small resort community 10 miles (16 km) from Apalachicola, Florida, were deemed unsafe due to their old age.

The original bridges opened in 1965; prior to that, visitors used a ferry to get to the island.

The eastern half of Gulf Beach Drive is now County Road 300.

"State Road G1A" was an analogue on the Gulf of Mexico to SR A1A on the Atlantic Ocean.

It is one of two x00 routes to not follow the numbering system - the other is SR 800, a short connection over the Intracoastal Waterway in Boca Raton.