Driving too slowly on Missouri highways can be illegal and may make you liable for accidents you cause. Missouri law prohibits drivers from operating their vehicles at speeds that impede the normal flow of traffic, and interstates in Missouri have a 40 mph minimum during normal driving conditions.
When a slow driver creates dangerous situations by forcing others to brake suddenly or by making risky passing maneuvers that lead to accidents, they can be held responsible for the resulting crashes.
Determining liability in slow driver accidents involves proving negligence and understanding Missouri’s comparative fault system. You may be able to recover compensation even if you rear-ended a dangerously slow driver, as fault often gets divided based on each person’s actions leading up to the crash.
Is Driving Too Slow Illegal in Missouri?
Yes, driving too slowly on Missouri highways is illegal when it creates dangerous conditions. Missouri law specifically prohibits drivers from operating their vehicles so slowly that they impede the normal flow of traffic.
The rule comes from RSMo § 304.011, which states that no person shall drive at a speed that impedes or blocks the customary and reasonable movement of traffic. This doesn’t give you an exact speed number, but it makes clear that your driving becomes illegal when it puts others at risk.
On Missouri interstates, there’s also a posted minimum speed of 40 mph under normal conditions. Driving below this limit without a valid reason violates state law and can result in a traffic ticket.
Slow driving becomes illegal in these situations:
Below posted minimums:
Traveling under 40 mph on interstates without mechanical problems or hazardous weather.
Impeding traffic flow:
Causing backups or forcing multiple vehicles to make dangerous passing maneuvers around you.
Left lane violations:
Staying in passing lanes while driving slower than the normal speed of traffic.
Creating hazards:
Driving so slowly that other drivers must brake hard or swerve to avoid hitting you.
The key is whether your slow speed creates an unreasonable danger to others on the road. Even if you think you’re being safe, the law requires you to consider how your actions affect everyone else.
What Is the Minimum Speed on Missouri Interstates
Missouri interstates have a 40 mph minimum on interstates during normal driving conditions. This applies to all lanes of travel unless a different minimum is posted in construction zones or urban areas.
However, the 40 mph rule isn’t absolute. Missouri follows what’s called the “basic speed rule,” which requires you to adjust your speed based on current conditions.
When weather or road conditions make 40 mph unsafe, you’re legally required to slow down. Heavy rain, dense fog, ice, or snow can all justify driving below the posted minimum.
| Road Condition | Required Speed | What This Means |
| Clear, dry conditions | 40 mph minimum | Must maintain at least 40 mph |
| Rain or light fog | Use judgment | Slow as needed for safety |
| Heavy snow or ice | Whatever’s safe | May be well below 40 mph |
| Construction zones | Follow posted signs | Temporary limits apply |
The law expects you to use common sense. If driving 40 mph would be dangerous due to conditions, then slowing down is the right thing to do.
Who Is Liable If a Slow Driver Causes a Highway Crash
A slow driver can absolutely be held responsible for causing an accident. Missouri uses a “pure comparative fault” system, which means each person involved gets assigned a percentage of blame based on their actions.
To prove a slow driver is liable, you need to show they were negligent. Negligence means they failed in their duty to drive safely, and this failure directly caused your accident and injuries.
Driving at a dangerously slow speed without a valid reason is a form of negligence because it creates unreasonable risks for other drivers. When someone travels far below the speed of surrounding traffic, they force others to react suddenly, change lanes, or brake hard.
Everyday Negligent Acts by Slow Drivers
Certain behaviors clearly indicate that a slow driver was negligent. These actions create unpredictable and dangerous situations on busy highways.
Sudden deceleration:
Slowing down abruptly without warning or an apparent reason.
Lane blocking:
Staying in the center or left lanes while driving much slower than other traffic.
No hazard lights:
Failing to warn other drivers when forced to travel at very low speeds.
Poor judgment:
Driving too slowly due to fog or other conditions increases the risk of rear-end collisions.
How Fault Gets Divided
Because Missouri uses comparative fault, blame often gets shared between drivers. Suppose you rear-end a much slower vehicle on an interstate at night that wasn’t displaying hazard lights.
A court might assign greater fault to the slow driver for creating a hazard while finding you partially at fault for following too closely. Even if you suffered significant damages, you may still be able to recover compensation for a portion of those losses.
The exact percentages depend on all the facts of your case. Our job is to gather evidence showing the slow driver’s actions were the primary cause of your accident.
Other Parties Who Might Share Blame
Sometimes liability extends beyond just the two drivers involved in the crash. Other parties could also be held responsible depending on the circumstances.
Employers: If a commercial driver was following unsafe company policies or driving a poorly maintained vehicle
Vehicle owners: If they knew about mechanical problems that prevented safe highway speeds
Government agencies: In rare cases involving dangerous road design or missing warning signs
Does the Rear Driver Always Pay in a Rear-End Crash
No, the rear driver doesn’t automatically pay for all damages in a rear-end collision. While the driver following in a rear-end collision often bears some responsibility, Missouri law considers the specific facts of each accident.
The front driver can be held mostly or entirely at fault in several situations. If they were driving at a dangerously slow speed without a good reason, failing to use hazard lights, or making sudden stops without warning, they may be primarily responsible.
Here’s when the front driver might be mostly to blame:
Unreasonably slow speeds:
Traveling far below traffic flow without mechanical problems or weather issues.
Missing safety signals:
Not using hazard lights to warn others of slow speeds.
Sudden braking:
Making abrupt stops without warning, sometimes called “brake checking“.
Equipment failures:
Driving with broken brake lights that don’t warn following drivers.
Missouri’s comparative fault system means even if you hit someone from behind, their negligent driving can significantly reduce your share of blame. You can still recover damages even if you’re found partially at fault.
What Evidence Proves a Slow Driver Was Negligent
Proving slow driver negligence requires solid evidence showing their behavior was unreasonably dangerous. Your word alone isn’t enough. You need concrete proof of what happened and why their actions caused your accident.
Scene Evidence
Physical evidence at the crash site is essential for reconstructing the events. This includes documentation of skid marks, where the length and location reveal reaction time and impact speed, and vehicle damage, which indicates the difference in speed between the vehicles at the moment of impact.
- Capturing road conditions shows whether weather or other factors legitimately justified the slow speed, and documenting traffic patterns establishes the normal flow of vehicles in that area.
Electronic Data from Vehicles
Modern vehicles store invaluable information that provides an objective record of the moments leading up to the crash.
This electronic data is often the most accurate evidence available. We seek information from Event Data Recorders (EDRs), or “black boxes,” which capture crucial speed, braking, and steering data.
- For commercial vehicles, GPS systems provide tracking that shows speed over time, and Dashcam footage from your car or others can offer undeniable visual proof of the negligence.
Witness Statements and Video
Third-party observations carry significant weight because witnesses have no stake in the outcome. We work to identify and interview everyone who saw the accident or the events leading up to it.
Potential sources include other drivers who had to pass the slow vehicle, traffic cameras from the Missouri Department of Transportation, and security cameras from nearby businesses.
Official Records and Documentation
Government records and professional reports help establish the complete picture of your accident. These documents often provide crucial context that supports your case.
Police reports: Officer observations about speeds and driver behavior.
Traffic citations: Tickets issued for impeding traffic or other violations.
Driver logs: Commercial vehicle records that might show fatigue leading to drowsy driving truck accidents.
Mechanical inspections: Reports confirming or denying claimed vehicle problems.
What If You Were Forced to Drive Slowly
Sometimes you have legitimate reasons for driving slowly that provide a complete defense against liability claims. Missouri law recognizes these valid exceptions when safety requires reduced speeds.
Mechanical Failure
If your vehicle suddenly breaks down, you may have no choice but to slow down. The key is how you handle the situation once problems develop.
You must activate hazard lights immediately to warn other drivers. Move to the rightmost lane or shoulder as quickly and safely as possible. Exit the highway at the first opportunity you can do so safely.
Keep all repair receipts and get written statements from mechanics documenting the problem. This evidence proves your slow speed was necessary, not negligent.
Weather and Road Conditions
Missouri’s basic speed rule requires you to slow down when conditions make normal speeds dangerous. In heavy rain, dense fog, snow, or ice, driving 40 mph is reckless.
During severe weather, reducing your speed is both legally required and the safest option. The law expects you to adjust for conditions, even if that means going well below posted minimums.
Slow Moving Vehicles and Farm Equipment
Missouri allows certain vehicles on highways despite their naturally slow speeds. Farm tractors, construction equipment, and horse-drawn vehicles have limited rights to use public roads.
These vehicles must display proper slow-moving emblems and yield to faster traffic when safe pull-offs are available. They’re following the law as long as they meet these requirements.
Medical Emergencies
A sudden medical event like a heart attack or seizure can force you to slow down unexpectedly. If this happens, activate hazard lights if possible and try to reach a safe location.
Call 911 for medical help and preserve all medical records documenting the emergency. These records prove your slow driving was due to circumstances beyond your control.
What Compensation Can You Recover After a Missouri Highway Crash
Missouri law allows you to seek compensation for all losses caused by a negligent slow driver. Your damages get divided into categories to ensure you’re made whole financially and personally.
Economic damages cover your verifiable financial losses. These include all medical bills from emergency treatment through future therapy, lost wages from missed work, vehicle repair costs, and other out-of-pocket expenses.
Non-economic damages compensate you for impacts that don’t have receipts. This includes physical pain and suffering, emotional distress, loss of enjoyment in life, and compensation for permanent injuries or scarring.
Punitive damages are rare but possible when a driver’s conduct is extremely reckless. If someone intentionally blocked traffic or caused an accident by driving slowly while intoxicated, you might recover additional money meant to punish their behavior.
Missouri generally doesn’t cap compensatory damages in injury cases (no cap on compensatory damages), so your recovery depends on proving the slow driver’s negligence and comprehensively documenting your losses.
How Long Do You Have to File a Claim in Missouri
Under Missouri law, you have five years statute of limitations from the date of your accident to file a personal injury lawsuit. This seems like plenty of time, but waiting can seriously hurt your case.
Evidence disappears quickly after accidents. Witness memories fade, security videos get erased, and vehicles are repaired or scrapped. The longer you wait, the harder it becomes to prove what really happened.
Insurance companies also have much shorter deadlines for reporting claims, often just days or weeks after the accident. Missing these deadlines can significantly complicate your case.
You need to document your injuries and connect them directly to the accident, which becomes more difficult as time passes. Medical records from right after the crash carry more weight than those created months later.
If you miss the five-year deadline, courts will almost certainly dismiss your case, and you’ll lose your right to any compensation.
Injured? Get Legal Help Today
At Beck & Beck Missouri Car Accident Lawyers, we understand the frustration of being injured by another person’s dangerous driving. You followed the rules, yet their negligent, slow driving caused your injuries and expenses.
We’re the only Missouri law firm focusing exclusively on auto accident law. This specialization means we know exactly how to prove slow driver negligence and fight for maximum compensation.
Our firm has a long history of helping victims navigate Missouri car accidents. Contact us today for a free consultation.
Frequently Asked Questions
Can I Get a Ticket for Driving Too Slow on Missouri Highways
Yes, you can receive a traffic citation for driving too slowly on Missouri interstates. The minimum speed is 40 mph under normal conditions, and violating this limit can result in fines and points on your license.
What Happens If I rear-end someone Going 20 MPH on the Interstate
The fault depends on why they were going so slowly. If they had no valid reason and weren’t using hazard lights, they’ll likely be found mainly responsible despite you hitting them from behind.
Are Slow Drivers in the Left Lane Breaking the Law
Yes, Missouri requires slower traffic to keep right. Driving slowly in the left lane when you’re not passing someone violates state traffic laws and can make you liable for resulting accidents.
Can Weather Justify Driving Below the Speed Limit
Absolutely. Missouri law requires you to drive at speeds safe for current conditions, even if that means going well below posted limits during storms or icy conditions.
What Should I Do If My Car Breaks Down on the Highway
Immediately turn on your hazard lights, move to the right shoulder if possible, and exit at the first safe opportunity. Document the mechanical problem with repair records to protect yourself legally.
Do Farm Tractors Have to Follow Highway Speed Limits
Farm equipment can legally use highways for short distances but must display slow-moving vehicle emblems and yield to faster traffic when safe areas allow them to pull over.
