In Montana, one of the largest and most sparsely populated states, it only makes sense for people to be able to drive faster. Going from one city to the next is often a 2+ hour affair, at speeds of 75 or 80. To go across the state takes many more hours. 200+ miles round trip for a weekend grocery shopping experience is common across the state.
On 2 lane highways, the limit is 70 in the day, 65 at night. This is close to reasonable, but 20 years ago, MT speed limits were "reasonable and prudent," meaning there was no real limit on the majority of highways, it was really up to you to deem what lived up to those words, and of course up to HP to make that call as well. New car and open road? Feel free to kick it up to 90 or 95.
Interstates are a different beast, especially recently. Initially the limit of 75 applied to all interstates (save for when they travel through cities, where they often drop to 60-70) but now there are many stretches of interstate that have 80 as the posted limit. As is the case anywhere, most drive over that limit. In MT, it seems there is a 10% rule-- you won't get a ticket if you don't go much over 10% higher than the posted limit. Still, there are plenty who will travel even faster than that.
What are the factors that should influence limits? Average travel distance, density of traffic, presence of controlled access and game fences, quality of highway/road, time of year, time of day, and finally something that I personally encounter--- quality/age of the vehicle. I have a new vehicle that I use for long distance travel, and it can easily handle cruise control notched off at 90 for a couple hours of flying across the plains, but many Montanans are rolling down the same roads in 20+ year old vehicles and big ass ranch trucks. Can there really be a single speed limit that makes sense for such a diversity of vehicles and conditions?
"Reasonable and prudent," a guideline that could morph depending on the conditions, season and vehicle type/age/quality, certainly makes sense to me. It worked well while enacted and was only dropped when the Feds threatened to stop pouring their dollars into the road infrastructure unless the state followed their speed limit guidelines. Too bad more don't see this adaptable method of policing roads as the more realistic option, especially considering how diverse our country is.
Now I must submit this post before I turn on the afterburners and pass the 1984 Ford with 3 different colored body panels, a missing tail light, and tires that are certainly not rated for 80 mph travel just so I am not stuck behind it when the tires blow! /s
edit: Long time Junior Member, just graduated and this is my first post as a Member!