All official U.S. road signs follow strict design standards set by the Federal Highway Administration (FHWA). The Manual on Uniform Traffic Control Devices (MUTCD) specifies that signs must use the FHWA Standard Alphabets, a series of typefaces designed for legibility at high speeds. The most common are Series B through Series F, with Series E Modified used for interstate highway signs.
In 2004, the FHWA approved an alternative font, Clearview, for use on positive-contrast signs (light text on dark background). Clearview was designed to improve readability, especially for older drivers. However, as of 2026, the FHWA still mandates the Standard Alphabets for most signs, and Clearview is optional for certain applications.
Sign shapes and colors are also standardized: red for stop and yield, yellow for warnings, green for guide signs, and blue for motorist services. The MUTCD is updated periodically, with the latest edition in 2023 incorporating minor changes but maintaining the core font and design requirements.
