The following two-digit United States Interstate Highways do not cross state lines. There is no real violation of any rule here - nothing says an interstate has to truly be inter-state, but it is an amusing violation of the phrase.

Interstate 4	- Tampa, FL (I-275) to Daytona Beach, FL (I-95)
Interstate 12	- Baton Rouge, LA (I-10) to Alton, LA (I-10)
Interstate 16	- Macon, GA (I-75) to Savannah, GA
Interstate 17	- Phoenix, AZ (I-10) to Flagstaff, AZ (I-40)
Interstate 19	- Nogales, AZ (Mexican border) to Tucson, AZ (I-10)
Interstate 27	- Lubbock, TX to Amarillo, TX (I-40)
Interstate 37	- Corpus Christi, TX (US-181) to San Antonio, TX (I-35)
Interstate 43	- Beloit, WI (I-39 & I-90) to Green Bay, WI (US-41)
Interstate 45	- Galveston, TX (TX-124) to Dallas, TX (I-30)
Interstate 49	- Lafayette, LA (I-10) to Shreveport, LA (I-20)
Interstate 73	- Candor, NC (US-220) to Greensboro, NC (I-40 & I-85)
Interstate 86	- West - Heyburn, ID (I-84) to Pocatello, ID (I-15)
Interstate 87	- New York, NY (I-278) to Champlain, NY (Canadian border)
Interstate 88	- West - Moline, IL (I-80) to Chicago, IL (I-290)
Interstate 88	- East - Binghamton, NY (I-81) to Schenectady, NY (I-90)
Interstate 96	- Muskegon, MI (US-31) to Detroit, MI (I-75)
Interstate 97	- Annapolis, MD (US-50) to Baltimore, MD (I-695)
Interstate 99	- Bedford, PA (I-70/I-76) to Bald Eagle, PA (US-220)

Of course, Alaska's and Hawaii's interstate highways are fully within that state's boundaries. And Puerto Rico is not a state, but it also has internal highways funded by the Federal Government.

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

Notes

• Interstate 73 may eventually reach Michigan
• Interstate 49 may eventually reach Kansas City, Missouri
• Interstate 45 may eventually extend through Oklahoma
• Interstate 99 may eventually extend through New York but it currently has no direct connection with any other interstate. Surface roads connect it with I-70/I-76 at its south end.

See also

• List of Interstate Highways
• List of gaps in Interstate Highways