Higher speed limits are associated with higher actual travel speeds.
From 1995 to 2005, rural interstate fatalities increased by an average of 9% following a 5 mph speed limit increase.
Since 2005, speed-related rural interstate fatality rates have decreased across states regardless of maximum speed limit.
Speeding is defined as driving above the posted limit or too fast for conditions (Insurance Institute for Highway Safety (IIHS) 2026). In 2023, speeding contributed to nearly 12,000 deaths, or 29% of all U.S. motor vehicle fatalities (IIHS 2026, National Highway Traffic Safety Administration (NHTSA) 2026). Speed limits are set by state and local transportation agencies based on factors such as traffic volume, roadway type, and population density (US Department of Transportation Federal Highway Administration (DOT FHWA) 2017).
Higher speed limits are associated with higher actual travel speeds, including in nearby areas with lower speed limits (Hu 2017). When UT raised the speed limit from 75 to 80 mph on specific interstate segments, average vehicle speeds on those segments increased from 72 to 78 mph. On segments where the speed limit remained 75 mph, average speeds increased from 72 to 76 mph.
In 2023, 40% of U.S. drivers reported exceeding interstate speed limits by 15 mph in the previous 30 days (American Automobile Association Foundation for Traffic Safety (AAAFTS) 2024). Forty percent of those surveyed also said it was unlikely they would be caught by police while speeding, and 20% said driving 15 mph over an interstate speed limit was either not at all or slightly dangerous.
In 1974 the rural interstate speed limit was reduced from 65 mph to 55 mph (Emergency Highway Energy Conservation Act of 1974). From 1973 to 1974, national road fatalities declined 16%, from 54,000 to 45,000 (Friedman et al. 2009). In 1995, Congress repealed national maximum speed limits altogether and delegated speed limit authority to the states (National Highway System Designation Act 1995). Except for Hawaii, all states raised rural interstate speed limits to at least 65 mph (Patterson et al. 2002).
From 1995-2005, rural interstate fatalities increased by an average of 9% in states that raised the rural interstate speed limits above 65 mph while fatalities declined by an average of 8% in states with a 65 mph speed limit (Friedman et al. 2009). Injuries in fatal crashes increased by an average of 12%.
Average speed-related fatality rates increased in MO and neighboring states that raised the rural interstate speed limit from 1995 to 2005. Six states (AR, KS, MO, NE, OK, and TN) increased the rural interstate speed limit in 1996 and saw an average increase from 0.08 to 0.13 fatalities per 100 million vehicle miles traveled (100M VMT) (NHTSA 1998, Figure 1). States that did not increase the speed limit (IL, IA, and KY) had a decrease from 0.24 to 0.17 fatalities per 100M VMT.
Figure 1. Speed-related Rural Interstate Fatalities per 100 million vehicle miles traveled (100M VMT) in MO and neighboring states, 1995-2023. Following the repeal of the national interstate speed limit, AR, KS, MO, NE, OK , and TN increased the rural interstate speed limit in 1996 (yellow). IA, IL, and KY kept the speed limit unchanged at 65 mph (blue) until 2014, 2005, and 2007, respectively. States that increased the rural interstate speed limit in 1996 saw an average increase in speed-related rural interstate fatality rates of 9%. States that kept a 65 mph speed limit after 1996 saw an average decrease in fatality rates of 8%. Since 2005, speed-related rural interstate fatality rates have decreased across states regardless of maximum speed limit changes (NHTSA 1995-2023, US DOT FHWA 1995-2023).
From 2005 to 2023, average speed-related fatality rates for MO and its neighboring states declined regardless of changes in rural interstate speed limits. AR, IL, IA, KS, and OK raised rural interstate speed limits by 5 mph and each state's fatality rate declined following the increase (NHTSA 2005-2023, US DOT FHWA 2005-2023). Fatality rate decreases ranged from 8% in IL to 74% in KS. MO, NE, and TN left their limits unchanged over the same period and recorded declines of 77%, 47%, and 69%, respectively. Human behavior, advances in vehicle safety technology, and enforcement of driver safety laws may contribute to changes in fatality rates (AAAFTS 2024, Islam et al 2024, Notrica et al 2020).
References
American Automobile Association Foundation for Traffic Safety (2024) 2023 Traffic Safety Culture Index.
https://aaafoundation.org/uploads/2026/01/202412-AAAFTS-2023-Traffic-Safety-Index.pdf
Arkansas Code 27-51-201 (2025) Limitations generally.
https://law.justia.com/codes/arkansas/title-27/subtitle-4/chapter-51/section-27-51-201/
Emergency Highway Energy Conservation Act (1974) 87 US Stat 1046.
https://www.govinfo.gov/app/details/STATUTE-87/STATUTE-87-Pg1046
Federal Highway Administration (1995-2023) Highway Statistics. US Department of Transportation.
https://www.fhwa.dot.gov/policyinformation/statistics.cfm
Federal Highway Administration (2017) Speed Limit Basics. US Department of Transportation.
https://highways.dot.gov/safety/speed-management/speed-limit-basics
Friedman LS, Hedeker D, Richter ED (2009) Long-Term Effects of Repealing the National Maximum Speed Limit in the United States. American Journal of Public Health, 99(9): 1626-1631.
https://pmc.ncbi.nlm.nih.gov/articles/PMC2724439/
Hu W (2017) Raising the speed limit from 75 to 80 mph on Utah rural interstates: Effects on vehicle speeds and speed variance. Journal of Safety Research, 61: 83-92.
https://www.sciencedirect.com/science/article/pii/S0022437517301408
Illinois Code Chapter 625 5/11-601 (2023) Rules of the Road.
https://law.justia.com/codes/illinois/2023/chapter-625/act-625-ilcs-5/chapter-11/
Illinois Code Chapter 625 5/11-601 (2005) Rules of the Road.
https://law.justia.com/codes/illinois/2005/chapter49/28620.html
Insurance Institute for Highway Safety (IIHS) (2026) Speed.
https://www.iihs.org/research-areas/speed
Iowa Code 321.285 (2025) Speed Restrictions.
https://law.justia.com/codes/iowa/title-viii/chapter-321/section-321-285/
Iowa Code 321.285 (2001) Speed Restrictions.
https://www.legis.iowa.gov/DOCS/IACODE/2001/321/285.html
Islam M, Hosseini P, Kakhani A, Jalayer M, Patel D (2024) Unveiling the risks of speeding behavior by investigating the dynamics of driver injury severity through advanced analytics. Science Reports, 14(1).
https://pmc.ncbi.nlm.nih.gov/articles/PMC11438865/
Kansas Session Laws (1996) Chapter 220.
https://kslegislature.gov/b2023_24/historical/1996/1996_O_SessionLaws_Chapter220.html
Kansas Statutes 8-1558 (2026) Maximum speed limits.
https://www.kslegislature.gov/b2025_26/laws/chapter/article/section/008_015_0058_k/
Kentucky Revised Statutes 189.390 (2026) Speed -- Secretary authorized to increase speed limit in certain areas by official order -- Parking.
https://apps.legislature.ky.gov/law/statutes/statute.aspx?id=52569
Kentucky Revised Statutes 189.390 (2006) Speed -- Secretary authorized to increase speed limit in certain areas by official order -- Parking.
https://law.justia.com/codes/kentucky/2006/189-00/390.html\
National Highway System Designation Act (1995) 109 US Stat 568.
https://www.govinfo.gov/app/details/STATUTE-109/STATUTE-109-Pg568/summary
National Highway Traffic Safety Administration (NHTSA) (1995-2023) Speeding Traffic Safety Facts. US Department of Transportation.
https://crashstats.nhtsa.dot.gov/#!/PublicationList/66
National Highway Traffic Safety Administration (NHTSA) (1998) The effect of increased speed limits in the post-MNSL era. US Department of Transportation.
https://rosap.ntl.bts.gov/view/dot/13774
National Highway Traffic Safety Administration (NHTSA) (2026) Overview of Motor Vehicle Crashes in 2024. US Department of Transportation.
https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/813791
Nebraska Revised Statute (2025) Speed; maximum limits; signs.
https://nebraskalegislature.gov/laws/statutes.php?statute=60-6,186
Notrica DM, Sayrs LW, Krishna N, Rowe D, Jaroszewski DE, McMahon LE (2020) The impact of state laws on motor vehicle fatality rates, 1999–2015. Journal of Trauma and Acute Care Surgery, 88(6): 760-769.
https://pmc.ncbi.nlm.nih.gov/articles/PMC7473820/
Oklahoma Statutes 47-11-801 (2025) Basic rule - Maximum and minimum limits – Fines and penalties.
https://www.oscn.net/applications/oscn/DeliverDocument.asp?CiteID=436892
Patterson TL, Frith WJ, Povey LJ, Keall MD (2002) The Effect of Increasing Rural Interstate Speed Limits in the United States. Traffic Injury Prevention, 3(4): 316-320.
https://www.tandfonline.com/doi/pdf/10.1080/15389580214625
RSMo 304.010 (1996) Definitions — maximum speed limits — cities, towns, villages, certain counties, may set speed limit, how set — slower speeds set, when — violations, penalty.
https://revisor.mo.gov/main/OneSection.aspx?section=304.010&bid=59265
Tennessee Code 55-8-152 (2025) Speed limits — Penalties.
https://advance.lexis.com/documentpage/?pdmfid=a780-4ec7-8ac9-c6f9b9d36538
