That depends, it's just under 80 miles on I-90 from the ID/WA border to the ID/MT border up north in the panhandle. Down south it is 408 miles on I-84
Arkansas is approximately 240 miles wide from its eastern border with Tennessee to its western border with Oklahoma.
The state of Montana is approximately 630 miles wide from its eastern border with North Dakota to its western border with Idaho. This measurement is taken from the widest point of the state, which is near the city of Plentywood in the east to the city of Trout Creek in the west. Montana is the fourth-largest state in the US by land area, covering over 147,000 square miles.
At its narrowest point Idaho is 50 miles wide.
Vermont is 37 miles wide at the southern border with Massachusetts
Kentucky is approximately 140 miles wide from its eastern border to its western border. The state's width varies slightly due to its irregular shape, but this measurement gives a general idea of its size.
It is about 70 miles from the eastern to western border of New Jersey.
Illinois is about 390 miles wide from the eastern border with Indiana to the western border with Iowa.
The Texas-Mexican border is approximately 1254 sq. miles.
Hells Canyon is a ten mile wide canyon located along the border of eastern Oregon and western Idaho.
Minnesota is approximately 200 miles wide at its widest point, stretching from the eastern border with Wisconsin to the western border with South Dakota. The state's shape is somewhat irregular, but this width gives a general idea of its size across the central part.
Montana is 630 miles wide.