No Left Turn sign
You may not turn left at this location. Continue straight or use another route.
Federal designation R3-2 in the MUTCD, the national standard every state signs to. Posted at intersections where a left turn would cross opposing traffic without a protected signal phase, or where the cross street is one-way against the turn.
How to recognise it
This sign is a tall rectangle in white, the standard background for a rule you must obey. These carry the force of law. Ignore one and you have broken a traffic rule, not just a guideline. Most are white rectangles with black text, and the handful that are not, the stop and yield signs, get their own unmistakable shapes.
What the test wants you to know
This sign bans the turn at all times unless a plaque underneath narrows it to certain hours, so do not assume it is only active during rush hour. It is a frequent one-way street companion, since turning left onto a one-way road often means turning straight into oncoming traffic.
Practise it
Reading about a sign is not the same as recognising it in half a second with an examiner watching. Every state road signs test on this site shows the sign and asks you to name it, then shows four faces and asks you to pick the right one.
Stop
Yield
Do Not Enter
Wrong Way
Speed Limit
One Way