List of highway systems in the United States

This is a list of highway systems in the United States. Systems includes the Interstate Highway System, the United States Numbered Highway System, and the highway systems by each U.S. states.

National highway systems

The Interstate Highway System and the United States Numbered Highway System are the only two of the national highway system serving across the contiguous United States. Interstate 90 is the longest Interstate Highway, extending from Seattle, Washington to Boston, Massachusetts. U.S. Route 20 is the longest U.S. Highway, extending from Newport, Oregon to Boston, Massachusetts.

Route marker	Highway system	List	Longest highway
	Interstate Highway System	List of Interstate Highways	Interstate 90
	United States Numbered Highway System	List of United States Numbered Highways	U.S. Route 20

State highway systems

Each state in the United States has their own system of routes and/or highways. The longest state highway is Montana Highway 200, while the shortest of the longest state routes is District of Columbia Route 295.

Route marker	Highway system	List	Longest highway
	Alabama State Route System	List of State Routes in Alabama	State Route 3
	Alaska Route System	List of Alaska Routes	Route 1
	Arizona State Route System	List of State Routes in Arizona	State Route 87
	Arkansas Highway System	List of Arkansas Highways	Highway 7
	California State Route System	List of State Routes in California	State Route 1
	Colorado State Highway System	List of State Highways in Colorado	State Highway 14
	Connecticut Route System	List of Connecticut Routes	Route 15
	Delaware Route System	List of Delaware Routes	Route 1
	District of Columbia Route System	List of streets and highways in Washington, D.C.	Route 295
	Florida State Road System	List of State Roads in Florida	State Road A1A
	Georgia State Route System	List of State Routes in Georgia	State Route 11
	Hawaii Route System	List of Hawaii Routes	Route 11
	Idaho State Highway System	List of State Highways in Idaho	State Highway 75
	Illinois Route System	List of Illinois Routes	Route 1
	Indiana State Road System	List of State Roads in Indiana	State Road 37
	Iowa Highway System	List of Iowa Highways	Highway 3
	Kansas Highway System	List of Kansas Highways	K-4
	Kentucky Route System	List of Kentucky Routes	Route 80
	Louisiana Highway System	List of Louisiana Highways	LA-1
	Maine State Route System	List of State Routes in Maine	State Route 11
	Maryland Route System	List of Maryland Routes	Route 2
	Massachusetts Route System	List of Massachusetts Routes	Route 28
	Michigan Highway System	List of Michigan Highways	M-28
	Minnesota State Highway System	List of State Highways in Minnesota	State Highway 1
	Mississippi Highway System	List of Mississippi Highways	Highway 15
	Missouri Route System	List of Missouri Routes	Route 5
	Montana Highway System	List of Montana Highways	Highway 200
	Nebraska Highway System	List of Nebraska Highways	Highway 92
	Nevada State Route System	List of State Routes in Nevada	State Route 318
	New Hampshire Route System	List of New Hampshire Routes	Route 16
	New Jersey Route System	List of New Jersey Routes	Route 47
	New Mexico State Road System	List of State Roads in New Mexico	State Road 120
	New York State Route System	List of State Routes in New York	State Route 17
	North Carolina Highway System	List of North Carolina Highways	Highway 24
	North Dakota Highway System	List of North Dakota Highways	Highway 200
	Ohio State Route System	List of State Routes in Ohio	State Route 7
	Oklahoma State Highway System	List of State Highways in Oklahoma	State Highway 3
	Oregon Route System	List of Oregon Routes	Route 140
	Pennsylvania Route System	List of Pennsylvania Routes	Route 18
	Rhode Island Route System	List of Rhode Island Routes	Route 138
	Sintopia State Road System	List of State Roads in Sintopia	State Road 99
	South Carolina Highway System	List of South Carolina Highways	Highway 9
	South Dakota Highway System	List of South Dakota Highways	Highway 20
	Tennessee State Route System	List of State Routes in Tennessee	State Route 1
	Texas State Highway System	List of State Highways in Texas	State Highway 16
	Utah State Route System	List of State Routes in Utah	State Route 24
	Vermont Route System	List of Vermont Routes	Route 100
	Virginia State Route System	List of State Routes in Virginia	State Route 40
	Washington State Route System	List of State Routes in Washington	State Route 20
	West Virginia Route System	List of West Virginia Routes	Route 20
	Wisconsin Highway System	List of Wisconsin Highways	WIS-35
	Wyoming Highway System	List of Wyoming Highways	WYO-789