In 1922, the six New England states devised a system to number its emerging highway system with a numbering system, replacing the confusing system the in use of painting colored bands and symbols on telegraph poles. Under this system, multistate interstate routes would have numbers less than 100, with odd numbered routes running eastwest, and even numbered routes northsouth. The directional rule wasnt followed very well, particularly for higher numbered routes. Numbers above 100 were for individual state highways, and could be duplicated among the states.

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