Everyday Engineering, a channel devoted to infrastructure education, explained the logic behind the interstate highway numbering system within the contiguous United States. Of course, there are a few exceptions such as those in Texas, Pennsylvania, and California. Additionally, Alaska, Hawaii, and Puerto Rico each have a system of their own.
In the US if the route is odd it’s a North/South route with the lowest numbers on the West coast and the highest numbers on the East coast. If the route number is even, it’s the East/West route, with the lowest numbers in the South and the highest numbers in the North. …and finally, just to confuse you, even more, Alaska, Hawaii, and Puerto Rico have their own numbering systems.