One possibility: Interstates are big roads that make it faster to get somewhere you could get on another road if you didn't mind going slower. Some (esp. rural

One possibility: Interstates are big roads that make it faster to get somewhere you could get on another road if you didn't mind going slower. Some (esp. rural) roads with 45+mph speed limits are the only way to get somewhere, therefor bikes need access. Anyway I'm also just waxing; I don't know the exact laws and surely there are exceptions- generally speaking "all but Interstate" seems like a reasonable thumbrule.