What are Primary Interstate Highways?
Q: What are Primary Interstate Highways?
A: Primary Interstate Highways are the major interstate highways of the United States and have a one or two-digit route number.
Q: How are even numbered routes assigned?
A: Even (0, 2, 4, 6, or 8) route numbers are given to east/west routes, with the smaller numbered routes in the south (I-10) and bigger numbered routes in the north (I-90).
Q: How are odd numbered routes assigned?
A: Odd (1, 3, 5, 7, or 9) route numbers are given to north/south routes, with the smaller numbered routes in the west (I-5) and the bigger numbered routes in the east (I-95).
Q: What is special about Interstates that end in 0 or 5?
A: Routes that end in a 0 or a 5 are major routes in the system. These Interstates generally go from coast to coast or from the bottom to the top of the U.S.
Q: What is an example of an Interstate Highway that goes from coast to coast?
A: For example, Interstate 5 goes from the Mexican Border at San Diego, California to the Canadian Border at Blaine, Washington. Likewise, Interstate 10 goes from Santa Monica on California's west coast to Jacksonville Florida on its east coast.
Q: What is longest Interstate Highway in US? A: The longest Interstate Highway in United States is I-90.
Q: How do three digit Interstates differ from two digit ones? A: Three digit Interstates are spur or loop Interstates that usually are located within big cities and areas outside of cities. The last two digits of a three-digit Interstate always correspond with its related two digit route number; if it begins with an odd number it is usually a spur route while if it begins with an even number it is usually a loop route.
