What does the bottom three-quarters of an INTERSTATE marker feature?

The bottom three-quarters of an INTERSTATE marker prominently display the route number in large white letters. This design is significant because it provides essential information to drivers, allowing them to quickly identify the specific interstate highway they are traveling on. The use of large white letters ensures high visibility and legibility, which is crucial for safety on the roads, especially at high speeds. Recognizing these route numbers helps drivers navigate effectively, plan their routes, and understand road signage as they travel across state lines. The clear presentation of route information enhances overall road navigation and supports efficient travel across the interstate system.