Slower traffic keep right sign: what it means

Slower traffic keep right sign: a white vertical rectangle with the words SLOWER TRAFFIC KEEP RIGHT in black
Drawing: Drivoku, based on MUTCD sign R4-3. Simplified; real signs follow the FHWA Standard Highway Signs specifications.

The SLOWER TRAFFIC KEEP RIGHT sign means that if you are driving slower than the traffic around you, you should use the right-hand lane.

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What does the SLOWER TRAFFIC KEEP RIGHT sign mean?

MUTCD Section 2B.38 says it may be used on multi-lane roads to improve capacity and reduce lane changing caused by slower vehicles that impede the normal flow of traffic. It is placed where some drivers tend to stay in the left lane below the normal speed of traffic.

Quick quiz

What does the sign at the top of this page mean?

  1. Stay in the right lane unless passing.
  2. One lane ends; move over in good time.
  3. Drive in the right lane if you are slower.

Show answer

C. Drive in the right lane if you are slower. Slower vehicles should use the right-hand lane (MUTCD Section 2B.38). Source: MUTCD 11th Edition, Chapter 2B, Regulatory Signs, Barricades, and Gates: Section 2B.38, FHWA; MUTCD 11th Edition, FHWA

Where will you see it?

On multi-lane highways, at the start of a multi-lane section or of an extra lane for slow vehicles. It should not be used near interchanges where traffic is entering or leaving.

What should you do?

If others are passing you on the right, move to the right lane when it is safe. Use your mirrors and signal before changing lanes.

What do people get wrong?

Thinking it only applies to trucks. It applies to any vehicle driving slower than the flow.

Common questions

Does it mean I must speed up?

No. It asks slower vehicles to use the right lane, so faster traffic can pass on the left.

Is there a sign just for trucks?

Yes. TRUCKS USE RIGHT LANE may be used as well (MUTCD Section 2B.38).

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Sources

Checked on 3 November 2026 against the MUTCD 11th Edition (FHWA), Section 2B.38.

  1. MUTCD 11th Edition, Chapter 2B, Regulatory Signs, Barricades, and Gates: Section 2B.38, FHWA
  2. 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.

This text was written with AI help, checked against the MUTCD and approved by Fri Vei AS. Last updated .

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