States consider updating U.S. speed-limit rules

Decades old rule still shapes speed decisions

On August 17, 2025, the Associated Press reported that U.S. speed limits still follow a decades-old rule. The rule ties posted limits to how most drivers already travel. That method often favors existing driving patterns over pedestrian safety or crash risks.

Road safety activists now press for changes. Local officials and some states want updated guidelines. They argue speed decisions should also weigh pedestrian exposure, crash history, and street activity, not just how fast cars move in free-flowing traffic.

The 85th percentile method explained

The 85th percentile rule emerged from the 1930s and 1940s studies of rural roads. Engineers tested how most cars traveled and then set posted limits accordingly. The method assumes the safest speed is what most drivers select, avoiding extremes.

In practice, officials measure how fast 100 cars travel. The 15th fastest car sets the marker. That number, rounded to the nearest five miles per hour, becomes the official speed limit posted on that roadway across different states.

Feedback loop from driver behavior

An Institute of Transportation Engineers brochure once said drivers could “vote with their feet” by driving faster than signs allowed. Over time, limits would rise to match. This idea fed a pattern of increasing posted speeds nationwide.

On August 17, 2025, Jenny O’Connell of the National Association of City Transportation Officials told the Associated Press that this creates a feedback loop. She said that when people speed, limits are raised to match that speeding behavior rather than lowered to reduce the crash risk.

FHWA clarifies rule in 2025 update

In December 2023, FHWA released the 11th Edition MUTCD, the manual’s first update since 2009, clarifying that the 85th percentile is not a mandate and urging context-based considerations.

In 2025, FHWA also published a Speed Limit Setting Handbook, reinforcing this approach. The agency stressed the 85th percentile was never a binding rule. Communities should also weigh safety risks and local context.

When setting limits, the new manual advised officials to consider pedestrians, street activity, and crash frequency. Leah Shahum of the Vision Zero Network said she wished the change had gone further, but admitted it had already shifted some state practices.

City Limits plan replaces old formulas

In 2020, the National Association of City Transportation Officials published “City Limits,” offering an alternative to the 85th percentile method. This approach sets limits by assessing street use, potential conflicts, and crash likelihood rather than driver speed alone.

By August 2025, the Associated Press reported the group’s argument that rural studies from the 1930s are outdated. NACTO said modern arterials and neighborhood streets demand limits set with pedestrian presence in mind, not just free-flowing car speed patterns.

Madison lowers limits in 2025 campaign

In summer 2025, Madison, Wisconsin, rolled out its “20 is Plenty” campaign. City workers swapped 25 mph signs for 20 mph on local residential streets. Officials said the intent was to reduce injury risks for pedestrians and cyclists nearby.

The Associated Press noted Madison’s move followed nationwide calls for context-based limits. Leaders said the lower numbers reflected school zones, parks, and neighborhoods, not driver speeds. Safety advocates view it as a model for other urban cities nationwide.

Seattle pilot back in 2018 showed results

Seattle tested reduced speed signs in 2018. According to the Vision Zero Network, its pilot cut serious injury crashes and dropped the measured 85th percentile speed by 7 percent. These results remain an example for advocates nationwide.

The Associated Press cited Seattle’s earlier program as proof that lower signs reduce harm. By using real injury data and not only driver speed surveys, the city demonstrated the benefits of changing how limits are set.

California shifts rules in recent years

California historically leaned heavily on the 85th percentile. In recent years, legislators have allowed local governments to depart from it if they documented a proven safety need. The Associated Press said advocates welcomed the move, though critics warned it was limited.

Kendra Ramsey of the California Bicycle Coalition told the Associated Press the change was progress but not enough. She said California still values cars over other road users and must prioritize pedestrian and cyclist safety.

Motorists group still defends percentile rule

The National Motorists Association defended the 85th percentile method. In August 2025, its policy director, Jay Beeber, told the Associated Press that minimizing car variations is safest. He argued that people will always drive the roadway’s natural speed anyway.

Beeber said it was unfair to build a road for 45 mph travel and then post a 30 mph sign. He said that ticketing drivers for using the designed speed makes enforcement unreasonable and undermines trust in traffic law systems.

IIHS study in 2019 ties speed to deaths

In 2019, the Insurance Institute for Highway Safety reported that every 5 mph rise in maximum limits increased interstate fatalities by 8.5 percent and other road deaths by 2.8 percent. These findings tied higher posted limits directly to greater crash risks.

Chuck Farmer, IIHS vice president for research, told the Associated Press that modern cars insulate drivers from a sense of speed. He said traveling 80 mph feels safe in newer vehicles, but carries far higher fatality risks in crashes nationwide.

National limits changed back in 1970s

During the oil embargo, Congress imposed a 55 mph national maximum speed limit in 1974. Fatalities fell 16.4 percent from 1973 to 1974 after the rule. Congress later allowed 65 mph before repealing the law in 1995, restoring state control.

After the repeal, states quickly raised limits. In 1995, many western states posted 70 mph or higher overnight. Critics said this rollback ignored safety warnings. Supporters called it a states’ rights issue. The debate continues through the 2025 legislative sessions.

Western states raise limits to 80 mph

As of August 2025, nine states allow 80-mph speed limits on at least some rural interstates (North Dakota joined in 2025), and Texas maintains the nation’s highest posted limit at 85 mph on part of SH-130. Nevada, Utah, and South Dakota are among the states that raised maximums the most in the past decade.

Texas holds the nation’s highest: an 85 mph stretch between Austin and San Antonio. North Dakota lawmakers also proposed 80 mph in 2023 and 2025, though former Governor Doug Burgum vetoed the plan in March 2023, citing safety concerns.

South Dakota’s rise in 2015 had mixed results

In 2015, South Dakota raised its maximum speed limit to 80 mph. Afterward, police reported more citations for extreme speeding over 100 mph. A 2017 Argus Leader analysis reviewed these patterns and raised questions about safety impacts statewide.

State data showed fatal crashes tied to speed were 20.7 percent in 2015, rose to 33 percent in 2016, dropped again in 2017, and climbed to 33.6 percent in 2018. Numbers varied, leaving debate unresolved about the’ full effect of higher speeds.

Ohio review of Mitchaw Road in March 2025

In March 2025, Sylvania Township, Ohio, asked county engineers to review Mitchaw Road near an assisted living facility, two schools, and a busy park. Resident Rose Hammond had long requested lowering the 55 mph limit to protect local pedestrians.

Engineers found the opposite. Based on the 85th percentile, the posted limit was 5 mph too low, suggesting 60 mph. Lucas County Engineer Mike Pniewski said data must guide choices. However, Ohio law fixed limits by roadway type instead.

Ohio adjusts guidelines in recent years

Ohio later adopted new flexibility. By 2025, the state will allow cities to consider the 50th percentile when many pedestrians or cyclists are present. Authorities also hired a consultant to compare practices with other states and suggest more context-based updates.

Michelle May, manager of Ohio’s highway safety program, said in August 2025 that states are slowly moving away from the 85th percentile as the gold standard. She said people live and travel differently than they did decades ago, requiring safety-focused decisions.

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Six states weighed bills in January 2025

On January 16, 2025, Land Line reported that lawmakers in six states proposed speed law changes early in the year. The Owner-Operator Independent Drivers Association said roads are safest when cars and trucks travel the same speed.

That report listed differentials in California, Idaho, Montana, Oregon, Washington, Arkansas, Indiana, and Michigan. Indiana’s HB1078 sought to equalize car and truck limits at 70 mph. Other bills in Mississippi, New Jersey, New York, North Dakota, and South Carolina targeted higher maximums.

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This slideshow was made with AI assistance and human editing.