The standard for signs, signals, and pavement markings in the United States. Includes HTML and .pdf versions.

Photograph collection of warning signs.

A listing of those most commonly used in the United States.

Official document of the United Kingdom. Includes illustrations and usage of signs and signals.

Advocacy group based in Washington, D.C., U.S. News, events, articles, and links.

Basic European signage.

Contains hundreds of images from around the world.

Website that accepts submissions of photographs of sign assemblies whose numbers can be arranged to form a mathematical operation.

U.S. organization which helps develop standards which are often applied to the Manual on Uniform Traffic Control Devices. History, member information, and meeting information.

Many humorous road signs, with commentary by the website maintainer.