US warning signs and their meanings

MUTCD Section 2C.02: warning signs are diamond-shaped, with a black legend and border on a yellow background, unless the manual says otherwise. Signs about pedestrians, bicyclists and playgrounds may be yellow or fluorescent yellow-green, and school signs are always fluorescent yellow-green.

Two warning signs have shapes of their own: the round railroad crossing advance warning sign and the pennant-shaped NO PASSING ZONE sign (Section 2A.05).

US warning signs

• Curve ahead signThe road curves ahead.
• Cross road signAnother road crosses yours ahead.
• Stop ahead signA STOP sign is coming up.
• Signal ahead signTraffic lights are ahead.
• Merge signTraffic will merge into your lane.
• Lane ends signOne lane ends; move over in good time.
• Divided highway signA median will split the two directions.
• Slippery when wet signThe road can be slippery when wet.
• Deer crossing signDeer may be on or crossing the road.
• Pedestrian crossing signPeople may be crossing ahead.
• School signA school area, zone or crossing is near.
• No passing zone signPassing is not allowed from here.
• Railroad crossing ahead signA railroad crossing is ahead.

Test yourself

Every sign page has its own quick question. Then see what to expect on the permit test.

More signs and markings

• Regulatory signs
• Guide and service signs
• Pavement markings
• All road signs

Sources

1. MUTCD 11th Edition, Chapter 2A, General (signs): Section 2A.05, FHWA
2. MUTCD 11th Edition, Chapter 2C, Warning Signs and Object Markers: Section 2C.02, FHWA
3. MUTCD 11th Edition, FHWA. FHWA lists the current version as the 11th Edition with Revision 1, dated December 2025

Sign pictures are our own simplified drawings of the MUTCD designs, which are in the public domain (MUTCD Section 1D.06). Sources and image credits.