Or (at one time) "reasonable and prudent".
Perhaps my favorite factoid about the state I grew up in is that prior to 1974 there was no set speed limit. When the Federal 55MPH limit was set, Montana's law defined speeding not as a moving violation, but as an "environmental waste of resources", and the fine was a flat $5 which didn't go on your record. The joke was to "keep a stack of fives on the dash" while driving through Montana.
In 1995 they re-instated the "reasonable and prudent" speed limit until it was struck down in 1998. During all of this there was no evidence that the lack of speed limits impacted fatalities.