When can you not make a u-turn other than the sign that says, don't?

If the sign is not there, it is OK. If it is there but hard to see, no U turn.

Depends on the state.

In Florida, you can make a u-turn unless a sign is posted saying you can’t.

If you’re pulled over for making a u turn where the sign is obstructed or down, you should take a photo of the obstructed sign with you to court.

First off, the photo is backwards. In the US we make U turns to the left, not to the right.

In Georgia, the law is this: it is always permitted (with attention to safety) unless there is a specific sign that forbids it. So 99% of the roads, it’s totally legal.

On the driving test, the answer would be – if the sign is obscured but partially visible, you are expected to follow the rule. If the sign is down or simply not visible, proceed with caution.

Around here, there is seldom ONE sign that says No U Turn – there are usually several – one in the middle of the road, one hanging from the wire, and maybe one across the other side. So there’s no excuse.

Check your local laws.
Here in Idaho it is illegal to make a U-turn unless there is a sign that says you can.
(Best to assume, I suppose, that any U-turn is illegal.)

You may not U turn by crossing a double yellow line in California. Oddly, you can turn left.

Thank you all.