What is the basis for naming highways?

Question

How did the transportation authorities name all the highways (interstates, US highways, state highways, county routes)? What is the basis of the Interstate highway numbering system?

Answer 1

Inter-state highways that run east to west end in an even # or 0, Route 90 route 10 as examples highways that run north to south end in an odd # Route 95 route 5 as examples.