What shape are interstate signs?

Interstate signs are shaped like a shield. This distinctive shape is designed to stand out and is specifically used for the identification of interstate highways. The shield shape has become a recognizable symbol for drivers, indicating the presence of a major highway that connects different states across the country. The use of this shape helps in quickly conveying vital information to motorists about the roadway they are traveling on, making navigation more intuitive. Other shapes, such as rectangles, circles, and diamonds, are used for different types of traffic signs with various functions, but the shield shape is unique to interstate routes.