The following highways are numbered 100A:

United States

County Road 100A (Bradford County, Florida) State Road 100 (SR 100) is a east–west highway serving northeast Florida. Its western terminus is at the Georgia- Florida border north of Avoca, Florida (its continuation in Georgia is State Route 11); its eastern terminus is an intersecti ...

County Road 100A (Columbia County, Florida) State Road 100 (SR 100) is a east–west highway serving northeast Florida. Its western terminus is at the Georgia- Florida border north of Avoca, Florida (its continuation in Georgia is State Route 11); its eastern terminus is an intersectio ...

County Road 100A (Union County, Florida) State Road 100 (SR 100) is a east–west highway serving northeast Florida. Its western terminus is at the Georgia- Florida border north of Avoca, Florida (its continuation in Georgia is State Route 11); its eastern terminus is an intersecti ...

Maine State Route 100A State Route 100 (SR 100) is a state highway in the U.S. state of Maine, running from Portland to Bangor. The south end of SR 100 is at the intersection of Forest Avenue and Cumberland Avenue in downtown Portland. Its north end is at th ...

New York State Route 100A * Vermont 100A

Vermont Route 100A Vermont Route 100 (VT 100) is a north–south state highway in Vermont in the United States. Running through the center of the state, it travels nearly the entire length of Vermont and is long. VT 100 is the state's longest number ...

{{Road index, 100A