[peckrob]

Around that same, the US implemented the National Maximum Speed Law [0], more commonly known at the "55mph speed limit" for the same reason.

It is widely regarded as one of the least popular pieces of legislation ever enacted by Congress, so hated that it even became the subject of a hard rock song [1]. It was widely ignored by motorists and police alike, with non-compliance rates as high as 85%. Some states made violations of the law basically meaningless, with the "fine" being a few dollars and no points or any other ramifications. It's also why cars over a certain age will have a big circle around the 55 on the speedometer.

What's crazy is that this wildly unpopular law soldiered on, in watered down form, until 1995, at which point speed limits fully reverted to state control. And, in retrospect, because of the widespread non-compliance it is believed that it did relatively little to impact overall fuel usage.

Interestingly, in Montana, there were some places that, prior to the 55 speed limit, had no speed limit. They were signed as "Reasonable and Prudent", and when the 55 speed limit was repealed, the "Reasonable and Prudent" signs went back up [2]. I have a picture of myself in front of one around that time because I was working as a park ranger in Yellowstone. This changed in 1999, and Montana now has a maximum speed.

[0] https://en.wikipedia.org/wiki/National_Maximum_Speed_Law

[1] https://www.youtube.com/watch?v=RvV3nn_de2k

[2] https://images.roadtrafficsigns.com/img/art/Montana-speed-li...

[mikestew]

Montana always had a "maximum speed", they just didn't put a number on it for periods of time. But if you thought 110mph down US 2 was reasonable and prudent (and there are plenty of sections where an argument could be made...), a MT trooper might set you straight.

[peckrob]

That makes sense. I remember hearing a story while I was out there of a race car driver that got ticketed doing like 130mph. His argument was that, for him, that was a reasonable and prudent speed. The State Trooper disagreed. :P

[ryukafalz]

It helps if you can practically enforce the restriction. Easy enough to tell if someone's driving a private car when the streets are otherwise mostly empty; hard to monitor everyone's speed and reliably pull people over if they go past the limit.