What does the U.S. abbreviation MUTCD stand for?

MUTCD stands for Manual on Uniform Traffic Control Devices.

The full federal title is Manual on Uniform Traffic Control Devices for Streets and Highways. Issued by the Federal Highway Administration within the U.S. Department of Transportation, it sets standards for the design, placement, and use of traffic signs, pavement markings, and traffic signals.

The manual is intended to make traffic-control devices predictable from one jurisdiction to another. It specifies details such as sign shapes, colors, lettering, signal arrangements, and the circumstances in which devices should be used. States may publish supplements or their own editions, but those versions must substantially conform to the national manual.

The first MUTCD was published in 1935 after earlier traffic-sign and safety organizations combined their work into a national standard. The modern manual is not the same system as the Vienna Convention: the United States has not ratified that convention, and American signs retain distinctive designs such as the red, white, and blue Interstate shield.