Road lines in United States
Double yellow in the middle
A double yellow centre line and white edges are the American pattern. On divided highways the left edge is yellow and the right edge white.
- Traffic in opposite directions is split by yellow paint, often a double line.
- On a divided highway the line on your left is yellow, the line on your right white.
- Canada does the same, so look at the signs and the speed limits too.
13 photos, grouped by the clue they show.
Key clue Double yellow centre line 4
Key clue Yellow left edge line 9
United States: what its road lines look like
American roads follow one simple rule: yellow paint separates traffic going in opposite directions, and white paint separates traffic going the same way. A two-lane road usually has a double yellow centre line, and a single dashed yellow where overtaking is allowed.
On a divided highway you only see traffic going your way, so the left edge line is yellow and the right edge line is white.
The same rule applies in every state, because a national manual sets the markings.
Look-alikes: how to tell them apart
United States vs 
Canada
Mexico
Canada uses the same colours in the same places, so look at signs and distances in kilometres. Mexico uses yellow too, and often paints its barriers and kerbs yellow as well.
Questions about road lines in United States
Why are American road lines yellow in the middle?
Yellow marks the divide between opposite directions of traffic. White lines separate lanes going the same way.
What does a double yellow line mean in the US?
A double solid yellow line means traffic in either direction should not cross it to overtake.