Speed Skip to content Vehicle ratings News Research areas About Home Research areas Speed Home Research areas Speed Speed Overview Dangers of speed By the numbers Who speeds? Speed limits Effects of speed limits on safety Speed safety cameras Traffic calming Intelligent speed assistance Overview The information on this page was compiled by Raul Avelar, a senior research transportation engineer at IIHS. Raul has authored multiple studies on speed and speeding prevention. Contact Raul. Around 11,000 deaths — 29% of all crash fatalities — occurred in speed-related crashes in 2024. High speeds make a crash more likely because drivers have less time to react and because it requires a longer distance to stop or slow down. They also make collisions more deadly because modest increases in speed cause large increases in crash energy. Raising speed limits leads to more deaths. People often drive faster than the speed limit, and if the limit is raised, they will go faster still. Research shows that when speed limits are raised, speeds go up, as do fatal crashes. By the same token, lowering speed limits cuts injury crashes. Speed safety cameras are an important tool. Numerous studies have shown that cameras reduce speeds and crashes on all types of roads. Latest news Latest news Vehicle ads flag performance, forget safety The proportion of vehicle ads focused on performance increased from 2018 to 2022, while a paltry few highlighted safety. May 12, 2026 How fleets can make the most of anti-speeding tech Fleet managers shared their experiences with intelligent speed assistance to help researchers identify best practices for implementing the technology. March 10, 2026 Dangers of speed Speed has a major impact on the number of crashes and the severity of injuries they cause (Elvik, 2005). It influences the risk of crashes and crash injuries in four basic ways: It increases the distance a vehicle travels from the time a driver detects an emergency to the time the driver reacts. It increases the distance needed to stop a vehicle once the driver starts to brake. It increases the risk that an evasive steering maneuver will result in loss of control. It increases crash energy disproportionately. For example, when impact speed increases from 40 to 60 mph (a 50% increase), the energy that needs to be managed increases by 125%. This additional energy needs to be absorbed and dissipated, challenging the vehicle structure and increasing the likelihood of severe injuries. For practical reasons, there are limits to the amount of crash energy that can be managed by vehicle structure, restraint systems (i.e., airbags and seat belts) and roadway hardware such as barriers and crash cushions. The higher the speed, the higher the likelihood that these limits will be exceeded in crashes, limiting the protection available for vehicle occupants and increasing the chances of severe injury. Some people contend that speed variation, not speeding, is the real danger. This idea is rooted in research conducted in the 1960s on two-lane rural roads, which found that vehicles traveling much faster or much slower than average were more likely to be involved in crashes (Solomon, 1964). However, that same research found that involvement in severe crashes increased with speed. While less speed variation is associated with fewer crashes because it cuts down on passing maneuvers and lane changes (Garber & Ehrhart, 2000; Transportation Research Board, 1984), the risk of death and severe injury is directly related to the speed at the time of a crash, not the speed difference between vehicles. Many differences in travel speeds are unavoidable because of the slower speeds of turning or merging vehicles. Higher speeds of other vehicles exacerbate this problem. Besides, many crashes and nearly half of those resulting in occupant deaths are single-vehicle impacts in which differences in speeds between vehicles play no role or only a minor one. By the numbers In 2024, a total of 11,288 deaths, or 29% of all motor vehicle fatalities, occurred in speed-related crashes. Based on a nationally representative sample of police-reported crashes, speeding — defined as exceeding the speed limit, driving too fast for conditions or racing — was involved in 8% of property-damage-only crashes and 13% of crashes with injuries or fatalities in 2024. The National Highway Traffic Safety Administration (NHTSA) estimates that the economic cost of speed-related crashes was about $46 billion in 2019 (Blincoe et al., 2023). In a 2025 national telephone survey conducted by the AAA Foundation for Traffic Safety, 48% of drivers said they had exceeded the speed limit by 15 mph on a freeway in the past month, and 37% reported exceeding the speed limit by 10 mph on a residential street (AAA Foundation for Traffic Safety, 2026). Who speeds? Drivers who speed tend to be younger than drivers who don’t, and male drivers are more likely than female drivers to speed (Preusser et al., 1988;Cosby et al., 2024; Williams et al., 2006). These trends hold true for fatal crashes involving speeding. Twenty percent of male passenger vehicle drivers involved in fatal crashes were speeding at the time of the crash in 2024, compared with 12% of female drivers. The proportion of drivers that were speeding in fatal crashes decreased with increasing driver age. Speed limits Speed limit laws, which date to 1901, traditionally have been the responsibility of the states, but the national maximum speed limit in place in the 1970s and 1980s effectively established maximum speed limits of 55 mph everywhere in the country. Since its complete repeal in 1995, speed limits have trended up. Currently, 21 states have maximum speed limits of 70 mph, and 11 states have maximum speed limits of 75 mph on some portion of their roadway systems. In eight states, 80 mph is the highest speed limit permitted on any road. A 41-mile stretch of Texas State Highway 130 has a speed limit of 85 mph. Maximum posted speed limits for different road types by state (table) State laws set maximum speed limits for each type of road (e.g., interstate highway, two-way undivided highway) and land use (urban or rural) (Federal Highway Administration, 2009). Statutory maximum speed limits also can be established for special situations such as school zones. The posted speed limit for a particular road or section of a road can be below the maximum speed limit allowed, however, if the local or state agency in charge of the road decides a lower limit is warranted. Lower speed limits Research summary for policymakers and advocates To set speed limits for specific roads, traffic engineers for decades relied heavily on the 85th percentile speed, which is the speed that 85% of vehicles are traveling at or below in free-flowing conditions. Recent work has highlighted the importance of other factors, such as roadway design and context, as well as the prevalence of pedestrians and bicyclists. The National Association of City Transportation Officials recommends a range of 10 to 25 mph for most city streets, based on reducing crash risk for pedestrians and cyclists (NACTO, 2020). A report by the National Cooperative Highway Research Program has suggested a range of criteria, including the 50th and 85th percentile speeds, vehicle and bicycle traffic volumes, geometric considerations, traffic control devices and the presence of parking (National Academies of Sciences, Engineering, and Medicine, 2021). The report considers different road types, ranging from local roads to freeways, and different contexts, ranging from rural to urban core. One problem with relying too much on the 85th percentile speed to set limits is that it’s a moving target. Numerous studies of travel speeds have shown that 85th percentile speeds on rural interstate highways increased when speed limits were raised and then continued increasing  (Najjar et al., 2000; Retting & Cheung, 2008; Retting & Greene, 1997; Retting & Teoh, 2008). When speed limits are raised to meet the current 85th percentile speed, a new, higher 85th percentile speed usually results. Effects of speed limits on safety The establishment of the national maximum speed limit and its subsequent repeal provided ample opportunity to study the effects of lowering and raising speed limits. Congress established the national maximum speed limit in 1973 in response to oil shortages. The U.S. Department of Transportation was directed to withhold highway funds from states that did not adopt a maximum speed limit of 55 mph. Before that, speed limits on rural interstates in most states ranged from 65 to 75 mph, with the majority of states setting rural interstate speed limits of 70 mph. In urban areas, most states maintained 55 mph speed limits before the national maximum speed limit was established. By March 1974, all states had adopted the 55 mph national maximum speed limit. Concerns about fuel availability and costs faded, however, and Congress in 1987 allowed states to increase speed limits on rural interstates to 65 mph. The National Highway System Designation Act of 1995 repealed the maximum speed limit, allowing states to set their own limits for the first time since 1974. Many states quickly moved to raise speed limits on both rural and urban interstates and freeways. Although the national maximum speed limit was imposed to conserve oil, its greatest effect was on safety. The National Research Council attributed 4,000 fewer fatalities to the decreased speeds in 1974 compared with 1973 (Transportation Research Board, 1984). Not surprisingly, higher limits established after the 1995 repeal were associated with immediate increases in travel speeds. For example, within one year after speed limits were raised from 55 to 70 mph on three urban freeways in Texas, the percent of passenger vehicles traveling faster than 70 mph increased from 15% to 50%; the percent exceeding 75 mph increased from 4% to 17% (Retting & Greene, 1997). On California urban freeways where speed limits were raised from 55 to 65 mph, the percent of motorists traveling faster than 70 mph increased from 29% to 41%. As limits continued to rise to 70, 75 and 80 mph, travel speeds continued to go up (Hu, 2017; Retting & Teoh, 2008). Fatalities also went up. Deaths on rural interstates increased 25%-30% when states began increasing speed limits from 55 to 65 mph in 1987 (Baum et al., 1989; Baum et al., 1990; Baum et al., 1991). In 1989, about two-thirds of this increase — 400 deaths — was attributed to increased speed and the rest to increased travel.  An IIHS study examined longer-term changes. During 1993-2017, a 5 mph increase in the maximum state speed limit was associated with an 8% increase in fatality rates on interstates and freeways and a 3% increase on other roads (Farmer, 2019). In total, there were an estimated 37,000 more traffic fatalities during these years than would have been expected if maximum speed limits in 1993 had remained in place. In 2017 alone, there were more than 1,900 additional deaths. The effect of speed limits on crashes and injuries isn’t limited to freeways. An IIHS study found that the risk of crashes with fatal, serious or evident injuries in Seattle dropped between 11% and 20% on arterial roads when the city lowered its default speed limit from 30 mph to 25 mph on arterial roads (Hu & Cicchino, 2024). Speed safety cameras Speed safety cameras, when used properly, can be an important tool for discouraging drivers from exceeding posted speed limits. Speed safety cameras Research summary for policymakers and advocates How they work Most speed safety cameras measure the speed of a vehicle at a single spot. Fixed cameras use either radar or detectors embedded in the road surface to measure a vehicle’s speed. Mobile cameras are placed at the roadside — for example in marked or unmarked police cars or containers or on poles — and use radar or laser to measure speeds. Som…