Edge line
A solid line along the edge of the roadway: white on the right-hand edge, and yellow on the left-hand edge of a divided highway, one-way street or ramp.
Easily confused with
How to read it
The MUTCD uses a normal width solid white line for the right edge of the roadway, and a solid yellow line for the left edge of divided highways, one-way streets and ramps. In the Manual's words, edge lines provide visual references to guide road users during adverse weather and visibility conditions. They are required on freeways, expressways and rural arterials at least 20 feet wide carrying 6,000 vehicles a day or more. Michigan's manual says solid white edge lines are often called fog lines and help drivers stay on the road at night or in bad weather.
Also searched as: white line on side of road, yellow edge line.
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.
Wider edge lines
The MUTCD allows wide edge lines for greater emphasis. The FHWA counts edge lines as wider when they grow from the minimum normal width of 4 inches to the maximum of 6 inches, and reports that wider edge lines can cut non-intersection fatal and injury crashes on rural two-lane roads by up to 37%.
At intersections and driveways
Edge lines stop across the side roads at an intersection, or continue as dotted extensions. The 2009 MUTCD did not continue them through intersections or major driveways and kept them unbroken for minor driveways. The 11th edition (2023) keeps them across driveways that don't meet its definition of an intersection.
Look-alikes
A solid white line between lanes is a lane line, not an edge line. A yellow edge line on the left is the usual place to see a single solid yellow line.
More road signs
Browse symbols drawn with lines.
Sources
- MUTCD 11th Edition, Part 3: Markings, MUTCD 11th Edition (December 2023), Part 3, U.S. Federal Highway Administration, Sections 3B.09, 3B.10, 3B.11
- MUTCD 2009 Edition, Chapter 3B: Pavement and Curb Markings, MUTCD 2009, Part 3, U.S. Federal Highway Administration, Section 3B.06
- What Every Driver Must Know, Michigan driver manual, Michigan Department of State, Chapter 5, p. 46
- Wider Edge Lines, Proven Safety Countermeasures, U.S. Federal Highway Administration, Office of Safety, Safety Benefits
Last reviewed October 2, 2026 by Rory Hansen. How we research