Slower Traffic Keep Right Sign

Updated July 9, 2026

Slower Traffic Keep Right · MUTCD R4-3 · Regulatory sign

What the Slower Traffic Keep Right sign means

This sign reminds drivers moving below the normal speed of traffic to stay in the right lane so faster vehicles can pass on the left. It appears on multilane highways and long grades where slow vehicles tend to bunch up traffic behind them. It does not give you permission to speed; it asks slower drivers to yield the left lanes for passing. On California highways the left lane is generally for passing, and lingering there while a line of cars piles up behind you is both discourteous and, in many cases, illegal.

What to do when you see it

If you are moving slower than surrounding traffic, stay in the right lane and leave the left lanes open for passing.

On the CA permit test

Slower Traffic Keep Right means slow vehicles belong in the right lane, not the left.

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