Primary (or main line) interstates are designated with a one- or two-digit route number. The route number is even for highways which are primarily east-west routes, and odd for highways which are primarily north-south. Spurs or loops off of the primary interstates are designated with a three-digit route number (see "Three-digit Interstates" below).

Table of contents

1 Continental U.S. Interstates 2 Hawaii Interstates 3 Alaska and Puerto Rico "Interstates" 3.1 Alaska 3.2 Puerto Rico 4 Interstates by U.S. State 5 Three-digit Interstates 6 Sources and external links

Continental U.S. Interstates

Interstate 4	Florida
Interstate 5	Washington, Oregon, California
Interstate 8	California, Arizona
Interstate 10	Florida, Alabama, Mississippi, Louisiana, Texas, New Mexico, Arizona, California
Interstate 12	Louisiana
Interstate 15	Montana, Idaho, Utah, Arizona, Nevada, California
Interstate 16	Georgia
Interstate 17	Arizona
Interstate 19	Arizona
Interstate 20	South Carolina, Georgia, Alabama, Mississippi, Louisiana, Texas
Interstate 24	Tennessee, Georgia, Tennessee (again), Kentucky, Illinois
Interstate 25	Wyoming, Colorado, New Mexico
Interstate 26	South Carolina, North Carolina, Tennessee
Interstate 27	Texas
Interstate 29	North Dakota, South Dakota, Iowa, Missouri
Interstate 30	Arkansas, Texas
Interstate 35	Minnesota, Iowa, Missouri, Kansas, Oklahoma, Texas
Interstate 37	Texas
Interstate 39	Wisconsin, Illinois
Interstate 40	North Carolina, Tennessee, Arkansas, Oklahoma, Texas, New Mexico, Arizona, California
Interstate 43	Wisconsin
Interstate 44	Missouri, Oklahoma, Texas
Interstate 45	Texas
Interstate 49	Louisiana
Interstate 55	Illinois, Missouri, Arkansas, Tennessee, Mississippi, Louisiana
Interstate 57	Illinois, Missouri
Interstate 59	Georgia, Alabama, Mississippi, Louisiana
Interstate 64	Virginia, West Virginia, Kentucky, Indiana, Illinois, Missouri
Interstate 65	Indiana, Kentucky, Tennessee, Alabama
Interstate 66	District of Columbia, Virginia
Interstate 68	Maryland, West Virginia
Interstate 69	Michigan, Indiana
Interstate 70	Maryland, Pennsylvania, West Virginia, Ohio, Indiana, Illinois, Missouri, Kansas, Colorado, Utah
Interstate 71	Ohio, Kentucky
Interstate 72	Illinois, Missouri
Interstate 73	North Carolina
Interstate 74	Ohio, Indiana, Illinois, Iowa
Interstate 75	Michigan, Ohio, Kentucky, Tennessee, Georgia, Florida (See Also: Alligator Alley)
Interstate 76	Eastern: New Jersey, Pennsylvania, Ohio; Western: Nebraska, Colorado
Interstate 77	Ohio, West Virginia, Virginia, North Carolina, South Carolina
Interstate 78	New York, New Jersey, Pennsylvania
Interstate 79	Pennsylvania, West Virginia
Interstate 80	New Jersey, Pennsylvania, Ohio, Indiana, Illinois, Iowa, Nebraska, Wyoming, Utah, Nevada, California
Interstate 81	New York, Pennsylvania, Maryland, West Virginia, Virginia, Tennessee
Interstate 82	Oregon, Washington
Interstate 83	Pennsylvania, Maryland
Interstate 84	Eastern: Massachusetts, Connecticut, New York, Pennsylvania; Western: Utah, Idaho, Oregon
Interstate 85	Virginia, North Carolina, South Carolina, Georgia, Alabama
Interstate 86	Eastern: New York, Pennsylvania; Western: Idaho
Interstate 87	New York
Interstate 88	Eastern: New York; Western: Illinois
Interstate 89	Vermont, New Hampshire
Interstate 90	Massachusetts, New York, Pennsylvania, Ohio, Indiana, Illinois, Wisconsin, Minnesota, South Dakota, Wyoming, Montana, Idaho, Washington
Interstate 91	Vermont, Connecticut, Massachusetts
Interstate 93	Vermont, New Hampshire, Massachusetts
Interstate 94	Michigan, Indiana, Illinois, Wisconsin, Minnesota, North Dakota, Montana
Interstate 95	Maine, New Hampshire, Massachusetts, Rhode Island, Connecticut, New York, New Jersey, Pennsylvania, Delaware, Maryland, Virginia, North Carolina, South Carolina, Georgia, Florida
Interstate 96	Michigan
Interstate 97	Maryland
Interstate 99	Pennsylvania
Interstate 238	California (an unusual exception to the rules)

Hawaii Interstates

The interstate highways in Hawaii are signed with the standard Interstate shield, with the letter "H" prefixed before the number. They are fully controlled-access routes built to the same standards as the continental US Interstate routes.

• Interstate H-1
• Interstate H-2
• Interstate H-3

The Federal Highway Administration funds four routes in Alaska and three routes in Puerto Rico under the same program as the rest of the Interstate Highway system. However, these routes are not required to meet the same standards as the mainland routes:

"Highways on the Interstate System in Alaska and Puerto Rico shall be designed in accordance with such geometric and construction standards as are adequate for current and probable future traffic demands and the needs of the locality of the highway." [1]

Alaska's "interstates" are signed as state routes -- and the state route numbers do not coincide with their "interstate" designation [1].

• Interstate A-1
• Interstate A-2
• Interstate A-3
• Interstate A-4

Like Alaska, Puerto Rico signs its "interstates" as territorial routes, and the numbers do not match the "interstate" designations. However, many of the territory's routes are access-controlled (though many are toll roads). [1]

• Interstate PRI-1
• Interstate PRI-2
• Interstate PRI-3

Three-digit Interstates

Three-digit interstates are generally discussed in the same article as their one- or two-digit "parent" interstate, even if plans to build the connection between the "spur" and the main highway never materialized. For example, I-170 is discussed in the I-70 article, and I-278 in New York and New Jersey is discussed in the I-78 article, even though no connection exists between I-78 and any of its spurs or loops.

I-238 is a notable exception because it is not a loop or spur of any one- or two-digit interstate (no I-38 exists, and if it did it would be nowhere near I-238). However, many other three-digit interstates also have separate Wikipedia entries. These routes' entries are (should be) linked from the parent route's page.

Sources and external links