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
At it's widest point (north border) Montana is roughly 550 miles wide.
At its narrowest point Idaho is 50 miles wide.
Vermont is 37 miles wide at the southern border with Massachusetts
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.
Montana is 630 miles wide.
The widest point of Maryland occurs at its northern border with Pennsylvania. The measured width there is about 250 miles.
The distance from the northern border of India to the southern border is 1,997 miles. The country is almost as wide as it is tall with the distance between the eastern and western borders being 1,822 miles.
260 miles wide
630 miles wide
430 miles long and 210 miles wide