What does the Reference Location sign (mile marker) mean?

The Reference Location sign (mile marker) (MUTCD D10-1, D10-2, D10-3) is a guide sign under the federal Manual on Uniform Traffic Control Devices, the national standard the states build from. A distance post rather than a route number: it says how far along the highway you have come, which is the quickest way to give a dispatcher your position.

Source: MUTCD 11th Edition (FHWA), checked 2026-09-09.

What shape and color is the Reference Location sign (mile marker)?

What a vertical rectangle means. Usually regulatory: a law you must obey. Speed limits, turn restrictions and parking rules take this shape. Rectangles are the loosely assigned outline in the system, though, so on this sign the shape alone does not tell you its family; the color and the legend do.

What green means. Permitted movements, direction, distance and destination guidance.

Guide and service signs. Direction, services, recreation: three colors doing three jobs, and not one of them carrying a duty. Work out which job the color does and most questions in this group answer themselves.

What is the Reference Location sign (mile marker) often mistaken for?

Exit numbers, which on many routes are derived from the same mileage. Enhanced Reference Location signs (D10-4, D10-5) may use blue or green and add the route shield.

What are the other guide and service signs?

US Route MarkerM1-4

Destination signD1-1, D1-2, D1-3

Distance signD2-1, D2-2, D2-3

Street Name signD3-1

Exit Gore signE5-1, E5-1a

Exit Number plaqueE1-5P, E1-5bP

EXIT ONLY panelE11-1d, E11-1e, E11-1f

Rest AreaD5-1, D5-1a, D5-2

HospitalD9-2

General Service signs (Gas, Food, Lodging, Telephone)D9-7, D9-8, D9-9, D9-1

All 11 guide and service signs on one page, or every US road sign by shape and color.

Test yourself on this sign and the rest of the set with a road signs practice test for Florida, Texas or California.

The artwork is the federal design itself, which the manual dedicates to the public domain in MUTCD 11th Edition, Part 1, Section 1D.06, checked 2026-09-09. The Interstate Shield, the 511 pictograph and the National Scenic Byway graphic are named exceptions and are not reproduced anywhere on this site.

Source: Manual on Uniform Traffic Control Devices, 11th Edition. Not affiliated with or endorsed by the Federal Highway Administration or any state agency.