Mile Marker sign
Shows the distance in miles from where the highway entered the state, counted from the south or west end.
Placed roughly every mile along most interstates and many state highways, almost always on the right shoulder.
How to recognise it
This sign is a tall rectangle in green, used only for directions and distances. Green for directions, distances and exits. They never tell you what to do, only where things are, which is the simplest way to remember the colour.
What the test wants you to know
Emergency dispatchers use this number to find a stranded driver or a crash when there is no other landmark around. The practical exam question is usually about what to read off during a roadside call, not about what the sign shows, so know your own mile marker before you need it.
Practise it
Reading about a sign is not the same as recognising it in half a second with an examiner watching. Every state road signs test on this site shows the sign and asks you to name it, then shows four faces and asks you to pick the right one.
Interstate Route Marker
US Route Marker
State Route Marker