List of Interstate Highways
There are 70 primary Interstate Highways in the Interstate Highway System, a network of controlled-access freeways in the United States. They are assigned one- or two-digit route numbers, whereas their associated "auxiliary" Interstate Highways receive three-digit route numbers. Typically, odd-numbered Interstates run south-north, with lower numbers in the west and higher numbers in the east; even-numbered Interstates run west-east, with lower numbers in the south and higher numbers in the north. Highways whose route numbers are divisible by "5" usually represent major coast-to-coast or border-to-border routes (ex. I-10 travels from Santa Monica, California, to Jacksonville, Florida, traveling from the Pacific to Atlantic oceans). Additionally, auxiliary highways have their numbering system where a different number prefixes the number of its parent highway.
Interstate 495 (Capital Beltway)
Interstate 495 (I-495) is a Interstate Highway that surrounds Washington, D.C., the capital of the United States of America, and its inner suburbs in adjacent Maryland and Virginia. I-495 is widely known as the Capital Beltway, or simply the Beltway, especially when the context of Washington, D.C., is clear. It is the basis of the phrase "inside the Beltway", used when referring to issues dealing with American government and politics. I-95 utilizes the southern and eastern half of the Capital Beltway to circumnavigate Washington, D.C., and is cosigned with I-495 along that portion.