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.
Transportation in Georgia (U.S. state)
The state of Georgia has of Interstate Highways within its borders. Georgia's major Interstate Highways are Interstate 16 (I-16), I-20, I-75, I-85, and I-95. Other important interstate highways are I-24 and I-59. I-285 is Atlanta, Georgia's perimeter route and I-575 connects counties in North Georgia to I-75. The Georgia Department of Transportation maintains only 16% of the roads in the state. The other 84% are the responsibility of the counties and cities; 75% of those roads are county roads.