maximum speed

National Maximum Speed Law

The National Maximum Speed Law in the United States was a provision of the 1974 Emergency Highway Energy Conservation Act that prohibited speed limits higher than 55 mph (90 km/h). This law was modified in 1987 to allow 65 mph (105 km/h) limits on certain roads.

The law was widely disregarded by motorists. Most states subversively opposed the law, ranging from proposing deals for exemption from it to minimizing speeding penalties.

This cap was intended to reduce gasoline consumption by 2.2% in response to the 1973 oil crisis. However, net fuel savings were calculated by the United States Department of Transportation at 1%, and independent studies found savings as low as half of one percent.

In 1995, the law was repealed, returning the power of setting speed limits to the states.


Before the federal speed limit

Historically, the power to set speed limits belonged to the states. Immediately before the National Maximum Speed Law became effective, speed limits were as high as 75 mph (120 km/h). (Kansas had lowered its turnpike speed limit from 80 before 1974.) Montana and Nevada generally posted no numeric speed limit on rural roads.

1974 — 55 mph National Speed Limit

As of November 20 1973, several states had modified speed limits:

  • 50 mph: Rhode Island, Maryland, Massachusetts, New Jersey, New York, Vermont, and Washington
  • 55 mph: North Carolina and Oregon
  • California lowered some 70 mph limits to 65 mph.
  • In late November 1973, Texas Governor Dolph Briscoe recommended adoption of a 55 mph statewide limit. On December 4, the Texas Highway Commission, with a 3-0 vote, adopted this 55 mph speed limit, citing unsafe speed differentials between the flow of traffic and people driving too slowly to comply with President Nixon's and Governor Briscoe's requests for voluntary slowdowns. The legality of the measure was questioned, and two Texas legislators threatened to sue to block the limit. However, by December 6, Texas Attorney General John Hill ruled that the speed reduction "'was in excess' of the commissioners' legal power," citing that a 1943 Texas Attorney General's opinion held that the legislature holds the power to set the statewide speed limit and the Commission's authority was limited to changing it in specific locales where safety factors required lower limits.

As an emergency response to the 1973 oil crisis, on November 26 1973, President Richard Nixon proposed a national 50 mph speed limit for passenger vehicles and a 55 mph speed limit for trucks and buses. That, combined with a ban on ornamental lighting, no gasoline sales on Sunday, and a 15% cut in gasoline production, were proposed to reduce total gas consumption by 200,000 barrels a day, representing a 2.2% drop from annualized 1973 gasoline consumption levels. Nixon partly based this on a belief that cars achieve maximum efficiency between 40 and 50 mph and that trucks and buses were most efficient at 55 mph.

The California Trucking Association, the then-largest trucking association in the United States, opposed differential speed limits on grounds that they are "not wise from a safety standpoint.

A uniform 55 mph (90 km/h) speed limit was signed by President Nixon on January 2, 1974, effective 60 days later, by requiring the limit as a condition of each state receiving highway funds, a use of the Commerce Clause of the United States Constitution.

The legislation required 55 mph speed limits on all 4 lane divided highways unless the road had a lower limit before November 1, 1973. In some cases, like the New York Thruway, the 50 mph speed limit had to be raised to 55 mph to comply with the law. The law capped speed limits at 55 mph on all other roads.

A survey by the Associated Press found that, as of the Wednesday, January 2, 1974:

  • 12 states already had maximum speed limits of 55 mph.
  • 9 states had maximum speed limits of 50 mph.
  • 29 states had to lower limits.

This includes some states that voluntarily lowered their limits in advance of the federal requirement.

On May 12, 1974, the United States Senate defeated a proposal by Senator Robert Dole to raise the speed limit to 60 mph.

Safety impact

It was believed that, based on a drop in fatalities the first year the limit was imposed, the 55 mph limit increased highway safety.

Other studies were more mixed on this point, and a Cato Institute report showed that the safety record actually worsened in the first few months of the 55 mph speed limit, suggesting that the fatality drop was a short-lived anomaly that regressed to the mean by 1978. After the oil crisis abated, the 55 mph speed limit was retained mainly due to the possible safety aspect.

In 1986, the highway death toll was roughly half that of 1966. The Insurance Institute for Highway Safety, which normally favors increased restrictions on drivers, said that credited "mainly" goes to laws passed 8 years before the 55 mph speed limit went into effect. Joan Claybrook was in "deep agreement.

Fuel savings

In 1986, the Heritage Foundation, a conservative think tank, reported that the United States Department of Transportation's Office of Driver Research found total fuel savings to be 1% and that "independent studies" found a half of one percent savings.

Opposition and noncompliance

The 55 mph limit was wildly unpopular. To wit:

  • The speed limit had very low compliance, reversing the commonly accepted practice that the speed limit should criminalize only the fastest 15% of drivers:
    • From April through June 1982, speed was monitored on New York's Interstate highways, and an 83% noncompliance rate was found, despite extreme penalties ranging from $100 (1982 dollars) or 30 days jail on a first offense to $500 (1982 dollars), up to 180 days in jail, and a six month driver's license revocation upon third conviction in 18 months.
    • In the 4th quarter of 1988, 85% of drivers violated the 55 mph speed limits on Connecticut rural interstates.
    • In 1985, the Texas's State Department of Highways and Public Transportation surveyed motorist speeds at 101 locations on six types of urban and rural roads. It found that 82.2% of motorists violated the 55 mph speed limit on rural interstates, 67.2% violated 55 mph speed limits on urban interstates, and 61.6% violated 55 mph speed limits on all roads.
  • Various states enacted legal measures to tiptoe around the 55 mph limit:
    • Arizona, Idaho, Montana, Nevada, and Utah replaced traditional speeding fines with $5-$15 energy wasting fines as long as drivers did not exceed the speed limit in effect before the 55 mph federal requirement.
      • Nevada's energy wasting fine was enacted on April 15 1981 when signed by Governor Robert List. Motorists not exceeding 70 mph in 55 mph zones could be issued $5 "energy wasting" fines. However, standard speeding tickets were still allowed and "troopers were directed not to take the new law as a signal to stop writing tickets".
    • In 1986, North Dakota's fine for speeding up to 15 mph over the 55 mph limit was only $15 and had no license points.
    • South Dakota cut speeding fines in 1985 and stopped assessing points for 10 or less than the speed limit in 1986.
    • Aug 1 1986, Minnesota, which normally suspended licenses after 3 tickets, stopped counting speeding tickets for no more than 65 (10 over).
  • In 1981, 33 state legislatures debated measures to oppose the 55 mph speed limit.
  • Some law enforcement officials openly questioned the 55 mph speed limit. In 1986, Jerry Baum, director of the South Dakota Highway Patrol, said "Why must I have a trooper stationed on an interstate, at 10 in the morning, worried about a guy driving 60 mph on a system designed to be traveled at 70? He could be out on a Friday night watching for drunken drivers."
  • Even organizations supporting the 55 mph limit, such as the American Automobile Association, provided lists of locations where the limit was strictly enforced.
  • On June 1 1986, Nevada ignored the 55 mph (90 km/h) speed limit by posting a 70 mph (110 km/h) limit on of Interstate 80. The Nevada statute authorizing this speed limit included language that invalidated itself if the federal government suspended transportation funding. Indeed, the Federal Highway Administration immediately withheld highway funding, so the statute quickly invalidated itself.

1987 and 1988 — 65 mph limit

In the April 2 1987 Surface Transportation and Uniform Relocation Assistance Act, Congress permitted states to raise speed limits to 65 mph (105 km/h) on rural Interstate highways.

In a bill that passed in mid-December 1987, Congress allowed certain non-Interstate rural roads built to Interstate standards to have 65 mph speed limits. As of December 29 1987 the states of California, Florida, Illinois, Iowa, Kansas, Kentucky and Oklahoma had applied for and been accepted into this program. The program was originally slated to last 4 years.

Reclassified roads

A few roads that weren't Interstate highways but were built to Interstate standards were designated as Interstate highways to qualify for the 65 mph speed limit:

1995 — Repeal of federal limits

Congress lifted all federal speed limit controls in the November 28 1995 National Highway Designation Act, fully delegating speed limit authority to the states. Several states immediately reverted to already existing laws. For example, most Texas rural limits that were above 55 mph in 1974 immediately reverted to 70 mph (110 km/h), causing some legal confusion before the new signs were posted. Montana reverted to non-numerical speed limits on most rural highways, although its legislature adopted a 75 mph (120 km/h) limit in 1999 (more information).

Hawaii was the last state to raise its speed limit above 55 mph when, in response to public outcry after an experiment with road safety cameras in 2002, it raised the maximum speed limit on parts of Interstates H-1 and H-3 to 60 mph.

Despite repeal of federal speed limit controls, current maximum speed limits are on average lower than in 1974:

  • States with same speed limit as pre-1974: 251
  • States with higher speed limit than pre-1974: 8
  • States with lower speed limits than pre-1974: 172

1Includes Texas where the same pre-1974 speed limits are applicable on the vast majority of rural roads despite some 75 and 80 mph limits. 2Includes Virginia where the vast majority of rural freeways have a 65 mph limit.

(Source: comparison of Reasonable Drivers Unanimous historical chart against Wikipedia Speed limits in the United States.)

55 mph speedometers

On September 1 1979, in a rulemaking that also regulated speedometer and odometer accuracy, the NHTSA required speedometers to have special emphasis on the number 55 and a maximum speed of 85 mph. However, on October 22 1981, the NHTSA proposed eliminating speedometer and odometer rules because they were "unlikely to yield significant safety benefits" and "[a] highlighted '55' on a speedometer scale adds little to the information provided to the driver by a roadside speed limit sign." (While odometer accuracy also has an economic benefit--more accurate sales of cars--the NHTSA's rules must have a clear safety benefit to be valid.)

Popular culture

The 55 mph limit morphed into the popular culture:

External photographs

Other reading

  • Singell, Larry D.; McNown, Robert F. (1985). "A Cost-Benefit Analysis of the 55 MPH Speed Limit: Reply". Southern Economic Journal 52 (2): 550–553.
  • Clotfelter, Charles T.; Hahn, John C. (1978). "Assessing the 55 m.p.h. National Speed Limit". Policy Sciences 9 (3): 281–294.


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