The speed limit on Interstate 90 in South Dakota is 80 mph or 128.7 km/h, except in city limits where the speed limit is lower, usually 55 or 65 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 speed limit in North Dakota depends on the type of road you are traveling on. It is 55 mph if you are on a gravel or dirt road, paved two lane county road and township highways if there is not a speed limit sign posted.It is 65 mph on a two lane highway if the posted sign says 65. It is 70 mph on paved four-lane divided highways. It is 75 if you are on Interstate 29 or interstate 94.
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They are as high as 65. In North Dakota, the speed limit is 65 mph on two-lane highways if posted for that speed.
As close to the posted speed limit as possible.
The highest speed limit I know of on an Interstate highway in the U.S. is 75 MPH, but that varies.
70 MPH on Interstate Highways.
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