In the United States, the U.S. Department of Transportation’s (USDOT)1 Federal Highway Administration (FHWA)2 publishes the Manual on Uniform Traffic Control Devices for Streets and Highways (MUTCD)3. The MUTCD is a compilation of national standards for all traffic control devices, including road markings, highway signs, and traffic signals.
Some states adopted the federal MUTCD as is, some states adopted the federal MUTCD along with a state-level supplement, and other states issued their own MUTCD. State-level supplements and MUTCDs are required, at a minimum, to conform to the federal MUTCD4.
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The MUTCD covers all traffic control devices installed on any street, highway, or bicycle trail open to public travel, including toll roads and roads within shopping centers, airports, sports arenas, and other similar businesses and/or recreation facilities that are privately owned but where the public is allowed to travel without access restrictions. It does not cover gated toll roads, roads within private gated properties where access is restricted at all times, parking areas, driving aisles within parking areas, and private highway/rail grade crossings.
You can download the MUTCD in PDF format5, for free, from the FHWA’s website. It will tell you more than you ever wanted to know about traffic signs and road markings.
Unless otherwise specified, all references to the MUTCD refer to the national MUTCD.
The 19th Century
Charles and Frank Duryea of Springfield, Massachusetts built and, on September 20, 1893, road-tested the first running, gasoline-powered American car.7
By the end of the 19th century, the automobile had arrived on the scene. It made convenient travel available for many people. As more people took to the roads, traffic control devices were developed to keep travelers moving safely and efficiently to their destinations.
The first traffic control devices were road signs. In the early days, folks out for a drive often ended up losing their way because directional signs were either nonexistent or broken or unreadable or knocked down.
In 1899, car owners in New York City met in the Waldorf–Astoria Hotel, at the corner of Fifth Avenue and 34th Street (current location of the Empire State Building) for the purpose of forming an automobile club—the predecessor of the American Automobile Association (AAA)8 and Canadian Automobile Association (CAA)9. One of the goals of the new club was to place and maintain signs on local highways to guide drivers around New York City and surrounding areas.
The 20th Century
In 1905, the Automobile Club of Buffalo began installation of an extensive signpost network throughout New York State.
In 1909, the Automobile Club of California installed highway signs within a 250-mile radius of San Francisco. Sometimes these were actual signs, but other times they were merely colored bands around a utility pole.
Auto clubs formed in other parts of the U.S. and started adding their own signs. Competition heated up as to which clubs would add signs to which routes. One study found that about half of the more traveled roads had as many as 11 different signage systems for one single route.
While automobile clubs were busy putting up road signs, other groups were designing traffic control devices.
The state of Michigan claims that a center line was first painted on a Michigan road in 1911. However, the California Department of Transportation claims that Dr. June McCarroll came up with the idea of painted lines. There is an historical marker at the corner of Indio Boulevard and Fargo Street in Indio, California that says, “… An encounter with a large truck on a narrow road in 1917 resulted in her Model T abandoning the road for a sandy ditch. This led Dr. June to the idea that a white stripe painted in the center of the road would make automobile travel safer. She personally painted the first known stripe in California on Indio Boulevard, then part of Highway 99, during 1917. A letter writing campaign initiated by the Indio Women’s Club eventually led to adoption of the practice by the California Highway Commission in 1924. …” See .
On August 5, 1914, the American Traffic Signal Company installed a traffic signal system at the intersection of East 105th Street and Euclid Avenue in Cleveland, Ohio.
In 1915, the first stop sign was put up in Detroit, Michigan.
On July 11, 1916, the (also known as the Bankhead–Shackleford Act) required that a state have a highway department before it can get federal money. This was the first federal highway funding legislation in the U.S.
In 1918, Wisconsin became the first state to install official route signs as part of its road maintenance duties.
In 1920, the first four-way, three-color traffic light was created by police officer William Potts in Detroit, Michigan.
Road signage was an unorganized mess. That led to representatives from Wisconsin, Minnesota, and Indiana working to develop uniform signs and road markings. In 1932, the group reported their results to the Mississippi Valley Association of Highway Departments (MVAHD). This was the beginning of standards for sign shapes.
The MVAHD decided to creates signs of various shapes to show the danger level of situations the drivers would encounter. The more edges a sign had, the greater the danger. (Round had the highest number of edges.) The biggest danger to drivers were trains. Railroad crossings got round signs. The next biggest danger was intersections where it was decided that octagonal signs would be used to tell drivers to stop before they go through the intersection. Diamond-shaped signs warned driver of places that required caution. Directions or other regulatory information was put on rectangular signs.
The signs were all white with black letters.
Due to the physical limits of sign-making equipment, there was a maximum width of two feet for the signs. The round and octagon shapes produced the most waste, so they were chosen for the fewest installations. Signs weren’t lighted in those days, so they figured drivers, even if they couldn’t read the signs, would recognize the shapes and respond accordingly.
In 1924, the first National Conference on Street and Highway Safety (NCSHS) proposed a color standard for traffic control devices:
* A red background with white letters meant stop.
* A yellow background with black letters meant caution.
* A green background with white letters meant proceed.
* A purple background with white letters meant there was an intersection.
* Black and white signs provided information on direction and distance. They were installed at every intersection and junction.
Also in 1924, the American Association of State Highway Officials (AASHO)—the forerunner of (AASHTO)—expanded on NCSHS’s efforts. AASHO felt that the yellow background with black letters offered superior visibility and advised its adoption for all danger and caution signs, including the stop sign. They thought red was too hard to see at night. They also proposed using the shield shape to designate U.S. highways.
1927 Manual and Specifications for the Manufacture, Display, and Erection of U.S. Standard Road Markers and Signs (for rural roads)
April 1929 Revision
December 1931 Revision
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Above: Manual and Specifications for the Manufacture, Display, and Erection of U.S. Standard Road Markers and Signs. First Edition. January 1927.
In January 1927, AASHO issued the Manual and Specifications for the Manufacture, Display, and Erection of U.S. Standard Road Markers and Signs. The manual addressed the use and design of signage for rural roads.
1930 Manual on Street Traffic Signs, Signals, and Markings (for urban streets)
Due to the shortcomings of a rural-only manual, following a national survey of existing traffic control devices, the Manual on Street Traffic Signs, Signals, and Markings was published specifically to address urban traffic control devices. The urban manual was more-or-less the same as the rural manual, but had extra information covering traffic signals, pavement markings, and safety zones. Some notable differences were that smaller signs were allowed in urban areas and the stop sign was modified to allow red letters on a yellow background.
While the two manuals were a good start, it quickly became apparent that having two separate manuals was confusing.
In 1932, NCSHS and AASHO formed the first Joint Committee on Uniform Traffic Control Devices (JCUTCD). In 1935, the first MUTCD was for distribution. By 1937, demand for the manual was so great that an actual printed version was published. The 1937 printed MUTCD was 166 pages long and separated into four parts covering signs, markings, signals, and islands.
It was the 1935 mimeographed version that outlined standard sign classifications: regulatory signs, warning signs, and guide signs. Regulatory signs had white backgrounds with black lettering—except for the stop sign: it had a yellow background with black lettering or a red background with yellow lettering. Diamond-shaped signs warned drivers to slow down. Square signs cautioned drivers about road conditions. Since nighttime lighting (street lights) was becoming more common, the manual also suggested adding symbols to the signs.
The 1935 MUTCD was the first to include pavement markings. For example, center lines were required on paved surfaces wider than 40 feet, on approaches to hill crests with a clear view of less than 500 feet, curves with a restricted view, or short-radius curves. The center lines could be white, yellow, or black, depending on which color was easiest to see. The manual clarified the number, color, and meaning of traffic signals. The 3-color traffic signal was adopted as the standard.
On November 7, 1935, the first edition of the MUTCD was approved as an American Standard.
A scan of the 1935 MUTCD can be found here: .
September 1937 Revision
February 1939 Revision
In 1939, the JCUTCD issued a 25-page supplement to the 1935 edition that recommended changes for sign lighting, speed signs, no-passing zone pavement markings, pedestrian signals, and how to determine if signs are needed in the first place. Although sign lighting was recommended, white reflectors (red for stop signs) could be used to illuminate all signs.
1942 MUTCD — War Emergency Edition
In 1942, a War Emergency Edition of the MUTCD described the types of traffic control devices to be used during wartime blackout conditions. Standards for traffic control devices were not changed for blackout conditions, per se, but when necessary, special blackout devices were to be used. The words we’re used to seeing on the pavement started out as a blackout device. The reflectorized beads we’re used to seeing in painted lines and words started out as a blackout device.
A scan of the 1942 War Emergency Edition of the MUTCD can be found here: .
September 1954 Revision
As the war wound down, it became apparent that the MUTCD needed to be rewritten. Work started on the peacetime edition in 1944 and was finalized and published in August 1948. The format of the manual was changed so that each traffic control device was addressed in only one place. Words were simplified where they could be and the squarish letters that were in common use were replaced by rounder letters.
In 1954, a 15-page supplement to the 1948 MUTCD was published. It included 47 revisions, along with an explanation of each one. The biggest change was that stop signs were changed to a red background with white letters. Guide signs were added to the existing regulatory and warning signs. The new Dwight D. Eisenhower National System of Interstate and Defense Highways (Interstate highways) got signs with green backgrounds and white letters.
In June 1961, the MUTCD was changed again. It was now 333 pages long and it had two new sections: a section on road construction and maintenance, and a section on civil defense signage. It also included additional signage and markings for the Interstate highways. The 1961 MUTCD can be found here: .
November 1971 Revision
April 1972 Revision
March 1973 Revision
October 1973 Revision
June 1974 Revision
June 1975 Revision
September 1976 Revision
December 1977 Revision
In 1971, the MUTCD was rewritten again. It added definitions for “shall”, “should”, and “may” requirements. Signs with orange backgrounds were added for construction and maintenance signage. Yellow markings separated traffic going in opposite directions. More symbols were added. School signs were added. The 1971 MUTCD can be found here: .
December 1979 Revision
December 1983 Revision
September 1984 Revision
March 1986 Revision
In 1978, the MUTCD added highway/rail crossings and traffic control devices for bicycles.
The MUTCD gets changed, added to, and/or fine-tuned as needed.
January 1990 Revision
March 1992 Revision
September 1993 Revision
November 1994 Revision
December 1996 Revision
June 1998 Revision
January 2000 Revision
2000 MUTCD — Millennium Edition
July 2002 Revision
November 2004 Revision
December 2007 Revision
May 2012 Revision
The most current version of the MUTCD is the 2009 Edition with Revision Numbers 1 and 2 incorporated, dated May 2012 .
Edit, April 10, 2019: Regarding the more edges a sign had, the greater the danger: currently, pentagonal (five-sided) signs are used for school zones and triangular (three-sided) signs are used for yield.
Currently, the following colors are used:
* Red is limited to stop, yield, and prohibition signs.
* A white background indicates a regulatory sign.
* A yellow background indicates a general warning message.
* A green background indicates permitted traffic movements or directional guidance
* A fluorescent yellow/green background indicates pedestrian crossings and school zones.
* An orange background indicates warning and guidance in roadway work zones.
* A coral background indicates incident management signs.
* A blue background indicates road user services, tourist information, and evacuation routes.
* A brown background indicates guidance to sites of public recreation or cultural interest.
 Bellis, Mary. “The Duryea Brothers of Automobile History”. ThoughtCo. September 6, 2017. < >.
- U.S. Department of Transportation (USDOT), 1200 New Jersey Avenue SE, Washington, DC 20590, 855-368-4200
- Federal Highway Administration (FHWA), 1200 New Jersey Avenue SE, Washington, DC 20590, 202-366-4000
- Manual on Uniform Traffic Control Devices for Streets and Highways (MUTCD)
- 23 CFR § 655.603 — Standards. — Title 23. Highways — Chapter I. Federal Highway Administration, Department of Transportation — Subchapter G. Engineering and Traffic Operations — Part 655. Traffic Operations — Subpart F. Traffic Control Devices on Federal-Aid and Other Streets and Highways Section — 655.603. Standards.
- “Manual on Uniform Traffic Control Devices for Streets and Highways. 2009 Edition with Revision Numbers 1 and 2 Incorporated. May 2012”. PDF format. Federal Highway Administration, U.S. Department of Transportation. May 2012.
- U.S. Patent 549,160 — Road-Engine
- Bellis, Mary. “The Duryea Brothers of Automobile History”. ThoughtCo. September 6, 2017.
- American Automobile Association (AAA)
- Canadian Automobile Association (CAA)