I'm looking at a list of Louisiana state highways, and we have a few that don't make any sense. Of course, we have the infamous dashed routes, usually the form XXX-X or XXXX-X. Since they're basically serving the purpose of a highway branching out, there are some oddities, like the LA 840-X family... we have LA 840-1 and 840-6, used to have a 840-3... but that's it, three numbers missing. We also have a LA 337 and 337-1, along with spurs that never meet each other. Any other instances of this across the country?
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