Note that linear markers on roads become incorrect when the road is diverted, re-routed or interrupted by new roads. For example, consider a new ring-road const

Note that linear markers on roads become incorrect when the road is diverted, re-routed or interrupted by new roads. For example, consider a new ring-road constructed to by-pass a town. However, US Interstates have special 3-digit numbering for ring-roads and other connectors. Luckily for you, America is not building any new infrastructure, so mileposts should be stable for some time.