You have seen the sign a thousand times. White rectangle, black letters: SLOWER TRAFFIC KEEP RIGHT. You have also seen the driver directly in front of it, doing 61 in the left lane, reading it like a fortune cookie.
So is "Slower Traffic Keep Right" actually a law, or just a very polite piece of sheet metal? Short answer: the sign itself is a regulatory sign, and in most states the rule behind it is written into state law. The details are where it gets fun.
What the Sign Officially Is
Road signs in the U.S. follow the federal Manual on Uniform Traffic Control Devices (MUTCD). Chapter 2B is the chapter on regulatory signs, the category that tells you what the rules are, as opposed to warning signs (curves, deer) or guide signs (exits, gas, that one Waffle House).
Section 2B.38 of the current edition covers three related signs:
- SLOWER TRAFFIC KEEP RIGHT (R4-3): may be used on multi-lane roads to improve capacity or cut down on unnecessary lane changing caused by slower vehicles blocking the normal flow.
- KEEP RIGHT EXCEPT TO PASS (R4-16): may be used where there are two lanes in one direction, to tell drivers to stay right unless they are actually passing.
- TRUCKS USE RIGHT LANE (R4-5): the same idea, aimed at the big rigs.
The MUTCD even says where these signs should go: at the start of multi-lane sections, and "at selected locations where there is a tendency on the part of some road users to drive in the left-hand lane (or lanes) below the normal speed of traffic." In other words, the federal government put a sign exactly where it expects you to camp.
The Law Behind the Sign
The MUTCD sets how signs look and where they go. The actual rule you can be cited for comes from state law, and almost every state has some version of it. A few examples, straight from the statutes:
- Virginia: Code § 46.2-804 says any vehicle going less than the normal speed of traffic must use the lane nearest the right edge when it is available, except when passing or preparing for a left turn. The listed fine is $100. Full breakdown in our Virginia left lane law post.
- Maryland: Transportation § 21-301 requires vehicles going 10 mph or more below the limit to use the right lane. It also says drivers slower than the general speed of traffic should keep right, and then specifically says no citation can be issued for that part. Maryland leans on the signs instead.
- Tennessee: put "keep right" in writing in its own statute. We covered it in Tennessee's left lane law.
So the honest answer is: the sign is real, it is regulatory, and the rule behind it is a law in most states. How strictly it is enforced, and for how much, depends on where you are. For a state-by-state list of places that actually write tickets, see 10 states that will actually ticket you.
"But I'm Doing the Speed Limit"
This is the most popular defense in left lane history, and in many states it does not hold up. Look at the wording: Virginia says "less than the normal speed of traffic," not "less than the speed limit." Maryland's softer rule uses "slower than the general speed of traffic." The rule is about being the slow one in the passing lane, not about whether you are personally in compliance with a number on a sign.
None of this means anyone should speed. It means the left lane is for passing, and when you are not passing, the right lane is waiting for you. It has been waiting a long time. It has feelings.
How to Obey the Sign Like a Professional
- Pass, then return. Finish the pass, signal, and move right when there is safe room.
- Merging onto the highway? Start right. The left lane is not the default lane.
- Getting passed? Hold steady and let it happen. Speeding up mid-pass is illegal in a lot of states.
- Unsure what "camping" even means? Here's what left lane camping means, in plain English.
Bring the Sign With You
If the highway sign isn't getting through, the Keep Right Unless Passing car magnet delivers the same message from your bumper, calmly, every mile. There's also a Keep Right window decal. Free shipping on orders $25+ (3 magnets gets you there).
This is why Left Lane Rehab exists.
This article is for general information and humor, not legal advice. Laws and fines change, so check the current statute or a licensed attorney for your situation.
Start your lane rehab today at leftlanerehab.com
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