White lane lines: what they mean

White lane lines diagram: a three-lane road with all traffic going one way, broken white lines between lanes, a solid white line on the right edge and a solid yellow line on the left edge
Diagram: DriveQuiz. Simplified, not to scale.

White lane lines separate lanes of traffic going in the same direction. A broken white line means you may change lanes with care; a solid white line means lane changes are discouraged.

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What it means

MUTCD Section 3A.03: white lines separate traffic flowing in the same direction or mark the right edge of the road. Section 3B.06: where you may cross with care, lane lines are broken white lines; where crossing is discouraged, they are solid white lines, for example on the approach to intersections to separate through lanes from turn lanes.

Edge lines (Section 3B.09): a solid white line marks the right edge of the road. On divided highways and one-way roads, a solid yellow line marks the left edge.

Where you see it

On multi-lane roads, on all freeways and Interstate highways, where lane lines are required (Section 3B.06), and on the approach to intersections.

A common mistake

Crossing a solid white line near an intersection because you are in the wrong lane. Go the way your lane goes and fix your route afterward.

Quick quiz

On a one-way road, which line marks the left edge?

  1. A solid yellow line
  2. A solid white line
  3. A broken white line
Show answer

A. A solid yellow line. Section 3B.09: on divided highways and one-way roads, the left edge line is solid yellow. Source: MUTCD 11th Edition, Part 3, Markings: Sections 3A.03, 3B.06, 3B.09, FHWA; MUTCD 11th Edition, FHWA

Compare with

Next in pavement markings: Two-way left-turn lane. See all pavement markings or the full road signs list.

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Sources

  1. MUTCD 11th Edition, Part 3, Markings: Sections 3A.03, 3B.06, 3B.09, FHWA
  2. MUTCD 11th Edition, FHWA. FHWA lists the current version as the 11th Edition with Revision 1, dated December 2025

Sign pictures are our own simplified drawings of the MUTCD designs, which are in the public domain (MUTCD Section 1D.06). Sources and image credits.