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.
Speed limits in the United States by jurisdiction
Non-Interstate divided highways (both freeways and expressways) have speed limits of 65 mph in rural areas and up to 60 mph in urban or suburban areas (NOTE: some non-interstate divided highways have gotten speed limit increases in November 2017 such as US Route 169 in the Twin Cities Metropolitan area). Rural two lane State and US highways in Minnesota have a default speed limits of 60 mph although many 55 mph speed limits are still in place after a traffic and engineering study from 2014-2019. County roads have speed limits of up to 55 mph for 2 lanes and 60 for divided sections.