The minimum speed on major routes (if any) varies by state. As an example, in many jurisdictions the minimum speed on a 65 MPH Interstate is 45MPH.
Most states have a catch-all rule that states you can be ticketed for driving at any speed that is so slow as to impede the flow of traffic.
The maximum legal speed limit on a rural Interstate highway is the posted speed limit in the United States. Each state in the United States has different posted speed limits for Interstate highways and other highways.
the speed limit is 65 mph, 70 when it is posted
This differs from state to state, but typically it is 65-70 mph
45 mph
40
45 mph
Auxiliary Interstate Highways and Primary Interstate Highways
70 MPH on Interstate Highways.
70 MPH
Most interstate highways were designed for the posted speed limits on those interstates.
On any Interstate highway the minimum speed you can travel is 45 mph. On some highways that were grandfathered into the system it can be as lows as 40 mph. On state roads the minimum speed is always posted if there is one. Otherwise the law states that you cannot drive at a speed that impedes the flow of traffic. That determination will be made by an officer of the law.
It can be from 60 to 85 mph.
Utah and Missouri. Actually, there are 5 Interstate highways in Utah and 17 in Missouri. The only state without any Interstate highways is Alaska.
45 MPH
There are several Interstate Highways with a 75 MPH speed limit at various points throughout their span, but there isn't one which has that speed limit at every single point.
The minimum will vary by locale, but will normally be either 40, 45, or rarely 50 mph for limited access highways. The minimum speed on the Interstate Highway System is either 40 or 45 mph and is set within each state based on road conditions and traffic levels.
The major highways are highway 50 highway 99 and highway 101 As well as Interstate 5, Interstate 40, Interstate 15, Interstate 8, and Interstate 80.