alt Hacker NewsAnd then read all the arbitrary historical minutia that have also influenced speed limits.
https://en.wikipedia.org/wiki/National_Maximum_Speed_Law
"...the National Maximum Speed Limit (NMSL) was enacted in the 1974 Emergency Highway Energy Conservation Act that withheld Federal Highway funds from States that refused to comply with provisions of the law, including a maximum speed limit of 55 miles per hour (89 km/h) for passenger vehicles, an increase Nixon approved in signing the final legislation."
Heh there is lots of minutiae, but I'd argue that the NMSL is actually a very big part of transport history in the US and is absolutely something that people should read about. I actually think covering it should be part of basic US civics but :shrug: doubt that's going to happen.