Divided Highway Begins Sign
MUTCD W6-1
The highway ahead is divided by a median; keep right.
What it looks like
A yellow diamond warning sign with a black symbol showing two opposing lanes separated by a median to indicate a divided highway begins.
When you'll see it
You see it where a two-way road becomes a divided highway with a median separating opposing directions of travel.
What to do
Keep right and stay on your side of the median as the roadway divides ahead.
Related signs
Source: Manual on Uniform Traffic Control Devices (MUTCD), 11th Edition — FHWA.