The following highways are numbered 100A:
State Road 100 is a 153-mile-long (246 km) east–west highway serving northeast Florida. Its western terminus is at the Georgia-Florida border four miles (6.4 km) north of Avoca, Florida ; its eastern terminus is an intersection with Shore Scenic Highway in Flagler Beach. The portion west of Lake City is only signed as portions of US 41 and US 129, both of which run north–south.
State Road 25 is a state highway in the U.S. state of Florida. It is mainly signed as U.S. Highways: