No Passing Zone, Color
The NO PASSING ZONE sign shall be a pennant-shaped isosceles triangle with its longer axis horizontal and pointing to the right. When used, the NO PASSING ZONE sign shall be installed on the left side of the roadway at the beginning of no-passing zones identified by either pavement markings or DO NOT PASS signs or both.
GalleriesAdvisory and Warning Signs
Federal Highway Administration Manual on Uniform Traffic Control Devices for Streets and Highways, 2003 Edition (including 2004 and 2007 revisions) (Washington, DC: United States Department of Transportation, 2007)