Most people assume slower driving automatically means safer driving. If speeding increases crash risks, then driving slower should make roads safer, too. But highways do not always work that neatly. This is especially true on interstates where traffic is already moving quickly and drivers are making split-second decisions based on the flow around them.
That is part of why transportation researchers have spent decades studying something called “speed variance,” essentially the difference between one vehicle’s speed and the overall speed of surrounding traffic. While speeding still contributes to thousands of deadly crashes every year, roadway studies and transportation agencies have repeatedly warned that unusually slow driving can create its own set of problems.
The issue has become noticeable enough that the National Motorists Association even designated June as “Lane Courtesy Month,” a campaign centered around passing-lane behavior and highway traffic flow. At the same time, states across the country have started tightening “keep right” laws and handing out steeper penalties for drivers who block traffic in passing lanes.
H&P Law reviewed federal crash statistics, transportation studies, roadway safety research, and state traffic laws to better understand how slow driving contributes to crashes, traffic conflicts, and dangerous chain reactions on American roads.
Slow Driving Becomes More Dangerous in the Passing Lane
Highways depend heavily on predictability, maybe more than most drivers realize. Drivers are constantly making small decisions based on what they expect the surrounding traffic to do. They anticipate how quickly vehicles are moving, whether someone is about to merge, or how much space they have before traffic slows ahead.
Once one vehicle starts moving substantially slower than the overall flow of traffic, especially in the left lane, that rhythm changes quickly. Almost instantly, cars pile up behind the slow driver. Some people will hit their brakes harder than intended, while some will attempt to find ways around the slower driver.
On busy highways, such behavior spreads quickly and results in something known to traffic engineers as a “rolling bottleneck.” This phenomenon has been discussed by researchers for many years now. According to research conducted by the Federal Highway Administration, speed variation is a larger contributing factor to traffic conflicts than speeding itself.
Interstate Highways Leave Less Room for Error
In cases where the state’s maximum speed limit is above the national average, the dangers are amplified as well. Nevada, Wyoming, South Dakota, Montana, and Texas all permit interstate maximum speeds up to 75 mph or above in certain locations, and drivers tend to drive over the speed limit in these instances.
With faster-moving traffic, a driver who travels significantly slower than other vehicles around them can create unsafe following distances rather easily, particularly at night or in traffic.
Federal crash data reviewed during this campaign showed that interstate highways accounted for the highest number of fatalities involving drivers traveling below expected traffic speeds. Between 2020 and 2024, there were 99 fatalities involving drivers traveling below the posted minimum speed limit on interstates alone.
Another 26 occurred on freeways and expressways, while 24 happened on principal arterial roadways. Overall, researchers identified 180 fatalities involving drivers traveling below the posted minimum speed limit across multiple roadway classifications during the review period.
Lane changes are thought to be responsible for about 10% of all accidents on highways, and when you consider the driver’s response to slower traffic, it becomes easier to envision.
Vehicles start changing lanes, and some drivers tailgate those in front of them due to increased frustration levels. Others attempt to merge into different lanes in an effort to avoid traffic. The slower-moving car does not necessarily cause the accident; rather, it creates situations that may lead to hazardous actions by motorists.
The Issue Is More About Traffic Flow Than Raw Speed
One reason this issue is considered quite controversial is that there are many drivers who believe slow driving equates to safe driving. At first glance, this does make sense. If speed causes more accidents, then slowing down will cause fewer.
However, traffic engineers argue that consistency is important. A driver who is traveling much slower than everyone else may unintentionally throw off the pace of all the other cars around them, especially on interstates.
That does not mean speeding is safe. It absolutely is not, and federal safety officials continue identifying speeding as one of the leading causes of fatal crashes nationwide. But researchers increasingly warn that very large speed differences in either direction, whether someone is driving much faster or much slower than surrounding traffic, can create dangerous conditions.
That really seems to be the larger point behind most of this research. The conversation is not about encouraging drivers to speed. It is about how unpredictable traffic flow can quickly trigger dangerous driving behavior from multiple surrounding vehicles.
Many Drivers Still Do Not Know Slow Left-Lane Driving Can Be Illegal
A surprising number of drivers do not realize that lingering in the left lane can actually violate traffic laws in many states. Every state allows motorists to use the left lane for passing, but many states also require slower-moving traffic to move right if it is impeding the normal flow of traffic.
Nevada, Colorado, Georgia, Florida, Louisiana, and Connecticut all enforce some version of these “keep right” laws. Some states apply those laws even when the slower-moving driver is technically traveling at or near the posted speed limit.
For years, many drivers viewed left-lane blocking more as an etiquette issue than an actual roadway safety matter. But transportation agencies increasingly see it differently because prolonged left-lane congestion often triggers the same risky behaviors that appear repeatedly throughout federal crash data: aggressive weaving, unsafe passing, tailgating, and abrupt lane changes.
Many Drivers Misunderstand Left-Lane Laws
Part of the confusion is that drivers interpret the passing lane differently. Some motorists believe that if they are traveling the speed limit, they have every right to remain in the left lane regardless of surrounding traffic conditions.
But many state laws focus less on the exact posted speed limit and more on maintaining the “normal flow of traffic.” That distinction confuses a lot of people because traffic flow and speed limits do not always perfectly align on busy interstates.
AAA polling in Virginia found that only 26% of drivers knew the state even had a left-lane law. At the same time, nearly half of the respondents reported regularly encountering slower drivers creating backups in the passing lane.
The same survey found that 57% of drivers frequently witness dangerous reactions caused by left-lane congestion, including tailgating, weaving, and passing on the right. Half of the surveyed drivers described prolonged left-lane blocking as dangerous behavior.
States Are Increasing Enforcement Efforts
While it may once have been more of a nuisance for drivers, it is becoming more of an enforcement issue as well. In 2025, for instance, there were more than 2,500 traffic stops made on the basis of blocking the traffic lane by the Colorado State Patrol. Connecticut, meanwhile, has also passed new enforcement measures that will go into effect in October 2026.
Georgia now allows penalties that can reportedly reach up to $1,000 and include license points for drivers impeding traffic in the left lane. Texas also permits fines for drivers improperly blocking passing lanes.
The broader shift reflects changing attitudes among transportation officials. Instead of focusing exclusively on speeding, many agencies are now emphasizing traffic predictability and lane discipline as part of overall roadway safety.
Slow Drivers Can Trigger Dangerous Reactions From Other Drivers
One of the major themes appearing throughout the crash data was how often slow-driving situations escalated into dangerous chain reactions involving multiple vehicles and multiple drivers making bad decisions at the same time.
The slower car isn’t always the cause of the accident. Sometimes a crash happens because another driver tailgates, makes aggressive lane changes, or attempts an unsafe pass to get around slower traffic. Once anger or frustration is added to the equation, things can quickly get out of hand.
Unsafe Passing and Lane Weaving Become Much More Common
Drivers trapped behind slower-moving traffic often start looking for openings anywhere they can find them. Some begin weaving aggressively between lanes, while others attempt passing maneuvers through gaps that are simply too small.
Between 2020 and 2024, federal crash statistics recorded 297 fatalities across 40 states involving drivers charged with “Improper, Unsafe Passing; or Passing on the Right.” Nevada alone accounted for eight of those fatalities.
Another 127 fatalities across 23 states involved drivers charged with wrong-side driving, passing violations, or following-related offenses during the same period.
There were also 2,920 fatalities nationwide involving improper or erratic lane changes between 2020 and 2024. Arizona recorded the nation’s highest fatality rate tied to erratic lane changes at 2.14 per 100,000 residents, followed by Ohio at 1.99 and Wyoming at 1.88.
Those numbers help explain why transportation agencies continue focusing so heavily on lane discipline and predictable traffic flow. Once drivers start weaving aggressively around slower-moving traffic, crash risks rise quickly.
Tailgating and Rear-End Crashes Often Follow
Rear-end collisions are another major part of this conversation because drivers approaching slower traffic at interstate speeds often have very little time to react safely once congestion suddenly forms ahead.
Between 2020 and 2024, a total of 385 deaths were recorded in 35 states where drivers were involved in cases of following too closely behind other cars. Among these figures, 123 deaths were recorded in Georgia, 36 in New York, and 30 in Ohio. Slowdowns due to tailgating or lack of reaction time become extremely dangerous in such situations.
According to reports from the DMV, New York records four out of every ten accidents as rear-end accidents. Roadway research conducted by the federal government has also revealed similar findings.
Frustration and Road Rage Can Escalate Quickly
Traffic frustration is nothing new, but the presence of slow-moving vehicles on highways is definitely a factor that affects aggressive behavior between drivers. This is supported by studies and statistics from the highways themselves.
- New Mexico recorded the nation’s highest road-rage incident rate in 2024 at 0.38 incidents per 100,000 residents.
- Tennessee followed closely behind with a road-rage incident rate of 0.32 per 100,000 residents.
- Delaware reported a rate of 0.29 incidents per 100,000 residents, placing it among the highest-ranking states nationally.
- Nevada recorded a road-rage incident rate of 0.24 per 100,000 residents. ConsumerAffairs® also reported that nearly 31% of Nevada traffic deaths were tied to aggressive or careless driving behaviors, roughly double the national average.
- Among Virginia drivers, 57% reportedly encounter aggressive behavior due to slow-moving vehicles in the left lane regularly, such as dangerous overtaking and weaving across traffic lanes.
According to AAA’s research, 96% of drivers reported exhibiting aggressive behaviors at least once within the year prior, and common reasons included traffic, stress, delays, and frustration.
None of this can excuse aggressive driving behavior. But it does show how one slower-moving vehicle can sometimes affect the behavior of dozens of surrounding drivers within seconds.
States With the Highest Fatality Rates Related to Slow Driving
Federal crash statistics reviewed during this campaign revealed major differences between states when it comes to fatalities involving unusually slow-moving interstate traffic.
Between 2020 and 2024, 42 states reported a combined total of 2,087 interstate fatalities involving drivers traveling 50 mph or less. Wyoming recorded the highest fatality rate at 0.58 per 100,000 residents, followed by South Carolina at 0.47 and Alabama at 0.35.
Louisiana, Florida, Virginia, Colorado, Ohio, California, and Pennsylvania also ranked among the states with the highest fatality rates associated with slow interstate driving. Nevada recorded a fatality rate of 0.18 during the review period, with 29 total fatalities tied to drivers traveling significantly below expected interstate traffic speeds.
Open-Road States Often Experience Larger Speed Gaps
Many of the states appearing near the top of these rankings share similar roadway conditions. Large rural interstate systems, long-distance highway travel, and higher posted speed limits all increase the likelihood of major speed differences between vehicles.
In open-road states where traffic commonly moves at 75 mph or faster, slower-moving vehicles can create dangerous closing distances very quickly. Drivers approaching slower traffic at interstate speeds simply have less time to react safely once congestion suddenly appears ahead.
On the other hand, it is critical for the roadway safety experts to remind everyone that speeding is one of the main reasons why there are many fatalities on the roads. What the data shows us is that the risk is not speeding but rather unpredictable traffic patterns and significant speed differences.
Some Impaired Drivers Are Not Speeding, They Are Driving Unusually Slowly
Most people picture impaired drivers as reckless speeders weaving aggressively through traffic. However, newer research suggests that impairment can sometimes look very different. As revealed by Traffic Injury Prevention in 2024, people under the influence of marijuana spent much more time driving slower than the speed limit while on simulated driving tests.
The Colorado Department of Transportation also revealed that close to 85% of the respondents reported driving less than eight hours after taking marijuana, while over 50% drove in one hour after consumption.
Impairment Does Not Always Look Aggressive
The studies conducted on the impact of marijuana use on road behavior have indicated that some users exhibit slow reaction time, poor concentration, inability to stay in lanes, and difficulty maintaining proper speed.
It is possible that these behaviors may lead to the same kinds of traffic problems experienced because of slow drivers in the left lane and the chaos associated with highway traffic flows. Driving much slower than other cars could lead to traffic snarls.
The results refute the popular belief that drivers under the influence of drugs only endanger themselves by speeding or erratic swerving. On the contrary, impaired behavior can take different forms and manifest itself as hesitant or inconsistent driving.
The Bigger Conversation Is About Traffic Predictability
Traffic systems work best when surrounding vehicles move in relatively expected ways. Sudden braking, erratic lane changes, rolling bottlenecks, and major speed differences all reduce the amount of time drivers have to react safely. However, this does not imply that low-speed driving is necessarily risky.
In situations involving intense rainfall, dense fog, snowfall, or construction sites, it might be essential to slow down and even become the safest possible action. Nevertheless, under normal circumstances on highways, transportation authorities stress the need to drive at a moderate speed relative to other vehicles around while driving safely and legally.
The crash data reviewed throughout this campaign suggests that the issue is not as simple as “speeding is bad, slower safer.” Much of the danger comes from unpredictable traffic flow and the chain reactions that can happen once traffic suddenly compresses or drivers start reacting aggressively around a slowdown.
How H&P Law Supports Nevada Drivers After Serious Traffic Crashes
Crashes on the highway resulting from unsafe passing, aggressive maneuvers in changing lanes, tailgating, and quick traffic slowdowns may cause severe injuries with extended recovery times for crash victims. As enhancing road safety becomes a priority throughout the country, dangerous driving practices on Nevada roads remain a major problem to be solved.
The Las Vegas car accident lawyers at H&P Law have recovered more than $100 million for injury victims and bring more than 60 years of combined experience representing clients involved in serious motor vehicle accidents throughout Nevada.
The firm handles cases involving highway collisions, truck accidents, unsafe lane changes, aggressive driving crashes, and other serious roadway incidents.
For individuals injured in Nevada traffic crashes, H&P Law offers free consultations and represents qualifying clients on a contingency fee basis.
