Standard Sign Shapes

Standard sign shapes and their assigned meanings:
 Circle - Exclusively for railroad advance warning signs
 Octagon - Exclusively for STOP signs
 Crossbuck - Exclusively for railroad grade crossing signs
 Pentagon - Used for school advance warning signs and county route marker signs
 Diamond - Used for warning signs
 Rectangle, Longer Dimension Vertical - Used for regulatory signs
 Rectangle, Longer Dimension Horizontal - Used for guide signs, some warning signs, and temporary traffic control signs
Trapezoid - Used for recreational area guide signs and National Forest route markers
 Equilateral Triangle, Point Down - Exclusively for YIELD signs
 Pennant - Exclusively for No Passing Zone signs
 Other shapes - Typically used for route marker signs