Since roughly the 1950s, all government-issued stop signs in the United States have been red. But you might be surprised to learn that for the 30 years prior, yellow stop signs were prevalent.

Blue stop signs are not issued by the U.S. Department of Transportation. Instead, they're often used on private property, especially in Hawaii.

An intersection with a two-way stop near Christie St. and St. Clair Ave. W. in Toronto. Each year in the United States, 700,000 police-reported crashes occur at stop signs.

Learn what blue stop signs really signify and how they differ from traditional red stop ... But while it’s rare, you might come across a blue stop sign, either on a United States roadway or abroad.