What are the standard dimensions of a stop sign?

The standard dimensions for a stop sign in the United States are 30 inches by 30 inches. This size is mandated by the Federal Highway Administration (FHWA) under the Manual on Uniform Traffic Control Devices (MUTCD) to ensure consistency and visibility for drivers. The 30 x 30 size allows the sign to be easily recognized from a distance, enhancing safety by effectively alerting drivers to make a complete stop at intersections.

Other dimensions mentioned in the options do not align with these established standards. For example, dimensions like 24 x 24 or 18 x 18 are too small to provide adequate visibility, and while 36 x 36 may seem larger, it is not the regulatory size designated for standard stop signs. Therefore, the 30 x 30 size is crucial for ensuring that traffic control devices are uniform and effective in guiding road users safely.