2. What is the Manual on Uniform Traffic Control Devices (MUTCD)?

http://mutcd.fhwa.dot.gov/kno-faq.htm

What is the Manual on Uniform Traffic Control Devices (MUTCD)?

The Federal Highway Administration (FHWA) publishes the MUTCD, which contains all national design, application, and placement standards for traffic control devices. The purpose of these devices, which includes signs, signals, and pavement markings, is to promote highway safety, efficiency, and uniformity so that traffic can move efficiently on the Nation's streets and highways.

What is the legal status of the MUTCD?

The MUTCD is adopted by reference in accordance with title 23, United States Code, Section 109(d) and Title 23, Code of Federal Regulations, Part 655.603, and is approved as the national standard for designing, applying, and planning traffic control devices.

 
Does this mean that all traffic control devices must comply with MUTCD standards?

Yes, all traffic control devices nationwide must conform to the MUTCD. There are no exceptions.