Stop signs are an essential part of road traffic control and safety. The familiar octagonal red sign that requires drivers to come to a complete stop is ubiquitous at road intersections across North America. However, stop signs were not always red. In fact, the original stop signs introduced in the early 20th century were yellow. So when and why did stop signs change from yellow to red?
The Origins of Stop Signs
Stop signs first began appearing in the late 19th century as a way to help control traffic at busy intersections. Early stop signs were quite varied in shape, size and color. Some were circular, some were triangular, others were rectangular. Colors ranged from black to yellow to blue and red.
In 1915, the American Association of State Highway Officials (AASHO) published standard dimensions and guidelines for stop signs in their Manual and Specifications for the Manufacture, Display and Erection of U.S. Standard Road Markers and Signs. This helped to standardize stop signs, recommending a 24-inch octagonal shape and using black letters on a white background.
By 1918, AASHO revised their guidelines to make stop signs yellow with black letters. Yellow was chosen because it is a high visibility color that stands out against most backgrounds. This helped make stop signs more noticeable to drivers. For the next couple decades, yellow became the standard stop sign color across the United States.
The Change to Red Stop Signs
In the late 1920s and early 1930s, there was a growing movement to switch to using red for stop signs instead of yellow. Red was argued to be even more visible and attention-grabbing. Some key developments that led to this change included:
- In 1927, the Mississippi Valley Association of State Highway Departments decided to change to red stop signs as their new standard.
- In 1930, the National Conference on Street and Highway Safety reviewed research that found red to be more visible than yellow, especially at night.
- In 1931, the American Engineering Council’s Joint Committee on Traffic Control Devices recommended adopting red as the standard stop sign color.
By 1935, the Manual on Uniform Traffic Control Devices established red as the national standard color for stop signs. The reasoning was that red is more visible, especially at night with the glare of headlights. Red also forces drivers to stop, while yellow was sometimes misinterpreted as a caution sign that could be rolled through.
How Red Became Universally Adopted
Despite red becoming the accepted standard, the transition from yellow to red took time as jurisdictions gradually replaced their old stop sign inventory. However, the transition accelerated significantly after World War II:
- Wartime rationing limited sign replacement from 1942-1945.
- In 1954, President Eisenhower launched the Interstate Highway System, requiring updated signage.
- TheMUTCD made red stop signs mandatory in 1961.
- The Highway Safety Act of 1966 tied federal funding to stop sign compliance.
Within just a couple decades, essentially all stop signs in the United States had changed from yellow to the now universally recognized red. Other countries like Canada, Mexico, the UK, Australia and New Zealand similarly adopted the red stop sign standard over the course of the 1950s and 1960s.
Rare Uses of Other Stop Sign Colors
Although red is almost always used for stop signs today, there are rare exceptions where other colors have been employed. These include:
- Small numbers of yellow stop signs still exist in some rural parts of the U.S.
- Green stop signs are occasionally seen at minor intersections in retirement communities with large elderly populations.
- Blue stop signs have been installed at some intersections near fire stations to ensure firefighters see them when rushing to calls.
- White stop signs are used in areas with frequent snowfall since the red signs can visually blend into the snow.
However, outside of these types of special situations, red reigns supreme as the global stop sign color standard.
Conclusion
Stop signs changed from yellow to red between the late 1920s and 1960s due to research showing that red is more visible and commanding. This change occurred through gradual adaptation, aided by national standardization efforts and legislation tying highway funding to sign compliance. While yellow and other colors are occasionally still seen, red is now the near universal color for stop signs across North America and the world. This simple change has had a major impact on traffic safety over the past 80+ years.
| Decade | Stop Sign Color |
|---|---|
| Late 1800s | Varied colors and shapes |
| 1910s-1920s | Yellow |
| 1930s | Shift from yellow to red begins |
| 1940s-1960s | Red fully adopted |
| Today | Red standard, with rare exceptions |
