No U-Turn Sign
MUTCD R3-4
U-turns are prohibited at this location.
What it looks like
A white square showing a black U-shaped arrow inside a red circle with a red slash through it, marking the movement as banned.
When you'll see it
Posted at intersections, medians, and divided-highway openings where reversing direction would block traffic or be hazardous.
What to do
You must not make a U-turn here; continue on and reverse direction only where it is legally allowed.
Related signs
Source: Manual on Uniform Traffic Control Devices (MUTCD), 11th Edition — FHWA.