Most detailed state road maps include tiny exit numbers corresponding to the small mile marker signs seen along the right side of the expressway. Markers on I-75 and other Interstates reset to "1" at state borders in the west or south and increase as the road heads eastbound and northbound.
For example, a driver heading south on Interstate 75 in Michigan who passes mile marker 209 is 209 miles from the Ohio border. A driver in Frankenmuth can quickly determine from the map that he is 65 miles away from exit 144.
Mile markers are also beneficial in determining a precise location in the event of an emergency. For example, a driver experiencing car trouble in an unfamiliar area can direct assistance to the nearest mile marker.