DETROIT – On Jan. 2, 1974, President Richard Nixon signed the Emergency Highway Energy Conservation Act into law.
The legislation capped speed limits on all roads at 55 mph. The New York Thruway had a speed limit of 50 mph at the time and was one of the few roads that actually had to raise its speed limit. This provision was drafted in response to the jump in the price of oil, as well as supply disruptions during the 1973 oil crisis.
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Connecticut passed the first speed limit for automobiles in 1901, with a urban speed limit of 12 mph and 15 for rural areas.
Michigan's 1st speed limit law
Michigan didn't have any state wide legislation on speed limits until early 1956 when the highway limit was made 65 mph during the day and 55 at night. Prior to this, speed limits were created and enforced by regional local governments and in some areas, drivers were allowed to determine what speed they felt safe driving.
The Emergency Highway Energy Conservation Act lowered Michigan's speed limit to 55 mph, to the chagrin of many drivers. The act prohibited the Department of Transportation from funding any projects within states that did not comply with the federal regulation.
Estimates by federal officials optimistically believed national gasoline consumption would drop more than 2 percent, but the actual savings were thought to be less than 1 percent.
Speed limits largely violated
By the mid 1980s, most traffic survey data revealed that these speed limits were widely violated nationwide. Ferrari enthusiast, musician and cookbook author Sammy Hagar famously publicly stated that "I can't drive 55" after receiving a traffic citation in rural New York.
In April 1987, the Surface Transportation and Uniform Relocation Assistance Act was passed, allowing states to raise speed limits to 65 mpg on rural interstate highways.
After the National Highway System Designation Act of 1995 was passed, Michigan raised the speed limit from 65 mph to 70 in 1996.
The speed limit was raised again in 2017, with some stretches of highways getting a bump to 75 mph.
Texas has highest speed limit
The current highest speed limit in the country and second-highest globally is a 41-mile section of Texas State Highway 130 at 85 mph.
Those that argue against the need for speed limits assert that higher speeds don't cause more collisions, which is true, car crash levels don't typically go up when speed limits do, but the collisions that do occur at higher speeds are more likely to be fatal. One of the largest causes of collisions is when vehicles move at different speeds, regardless of the speed limit.
Michigan speed limits are based on a formula that uses the 85th percentile of free-flowing traffic, the speed which no more than 15 percent of traffic is exceeding. The idea behind this is that the majority of citizens are assumed to be reasonable and safe drivers, and so the limits would cater to these citizens.
You can find a traffic map with collision and construction information around Ann Arbor here and for the rest of Metro Detroit here.