Final answer:
An even-numbered interstate sign usually indicates that the highway runs east-west. Even-numbered interstates like I-10 traverse the country horizontally, while odd-numbered interstates run vertically.
Step-by-step explanation:
If an interstate sign has an even number, it typically indicates that the highway runs primarily in an east-west direction. In the United States, interstate highways use a numbering system that helps in identifying the direction and the purpose of the highway. Even-numbered interstates run east and west, while odd-numbered interstates run north and south. For example, Interstate 10 (I-10) runs east-west across the southern United States, from California to Florida.
Interstate signs with even numbers typically indicate that the highway runs east-west. This is because historically, the odd-numbered highways were assigned to north-south routes, while the even-numbered highways were assigned to east-west routes. For example, Interstate 80 runs across the country from California to New Jersey, making it an east-west highway.