Final answer:
Interstate routes in the United States primarily run in an east-west or north-south direction, connecting major cities and regions across the country.
Step-by-step explanation:
Interstate routes in the United States primarily run in an east-west or north-south direction, rather than diagonally or in a circular pattern. This is because the interstate highway system was designed to connect major cities and regions across the country. For example, Interstate 90 runs from Seattle, Washington, in the west to Boston, Massachusetts, in the east, while Interstate 75 runs from Miami, Florida, in the south to Sault Ste. Marie, Michigan, in the north.