Mile marker
A small green vertical sign reading MILE above a number. It shows how many miles along the highway the spot is, counted from the state line or the start of the route.
How to read it
The MUTCD calls it a reference location sign (D10-1 to D10-3, by the number of digits). It is required on freeways, and on expressways that keep continuous mileage, to help drivers judge their progress, to give a way of pinpointing crashes and other emergencies, and for maintenance. On freeways it has white numerals 10 inches high on a green panel 12 inches wide. Smaller intermediate signs with a decimal point may mark tenths of a mile in between. Pennsylvania's manual points out that knowing the mile marker gives an approximate location to pass on when calling for roadside assistance. This page describes the national standard; it isn’t legal advice, and each state applies it on its own roads.
Also searched as: mile marker 0, mile markers, mile marker sign, reference location sign.
Rules vary by state and country. This explains the sign's standard meaning in the U.S. Manual on Uniform Traffic Control Devices; it isn't legal advice.
Where mile 0 is
Zero is at the south or west state line, or at the south or west end of a route that begins inside the state, and the numbers rise going north or east. Pennsylvania's manual says entering the state from the west on I-80, the markers start at Mile 1 and increase eastward. The count starts again at each state line, and where two routes share a road only one keeps its numbering, the Interstate if one of them is. On a divided highway the miles are measured on the northbound or eastbound side, with the opposite markers set directly across.
Exit numbers come from the same count
Freeway exit numbers follow the mile markers, so an exit's number is its mile point. Florida's handbook says its Interstate mile markers match the exit numbers.
Should or shall
In the 2009 MUTCD, starting zero at the south and west state lines was guidance (should). The 11th edition (2023) makes it a standard (shall), and allows the intermediate signs every tenth, two tenths or half mile.
More road signs
Browse symbols drawn with letters and numbers.
Sources
- MUTCD 2009 Edition, Chapter 2H: General Information Signs, MUTCD 2009, Part 2, U.S. Federal Highway Administration, Section 2H.05
- MUTCD 11th Edition, Chapters 2H–2N: General Information Signs to Changeable Message Signs, MUTCD 11th edition (December 2023), Part 2, U.S. Federal Highway Administration, Section 2H.11
- Pennsylvania Driver's Manual, Chapter 2: Signals, Signs and Pavement Markings, Pennsylvania Department of Transportation, p. 20
- Official Florida Driver License Handbook, rev. 08/2023, Florida Department of Highway Safety and Motor Vehicles, p. 47
- MUTCD 2009 Edition, Chapter 2E: Guide Signs—Freeways and Expressways, MUTCD 2009, Part 2, U.S. Federal Highway Administration, Section 2E.31
Last reviewed October 2, 2026 by Rory Hansen. How we research