List of highways numbered 21A

Route 21A, or Highway 21A, may refer to:

India

 * NH21A-IN.svg National Highway 21A (India)

United States

 * Clay County Road 21A FL.svg County Road 21A (Clay County, Florida)
 * M-21A 1926.svg M-21A (Michigan highway) (former)
 * N SPUR 21A.svg Nebraska Spur 21A
 * Ellipse sign 21A.svg New Jersey Route 21A (former)
 * NY-21A (1927).svg New York State Route 21A (former)
 * Suffolk County Route 21A NY.svg County Route 21A (Suffolk County, New York)
 * Sullivan County Route 21A NY.svg County Route 21A (Sullivan County, New York)
 * Warren County Route 21A NY.svg County Route 21A (Warren County, New York)
 * WA-SSH21-A.svg Secondary State Highway 21A (Washington) (former)