The Counties That Sit On A State Line

Every state has counties pressed up against a neighbor's laws, and the effects are concrete. Fireworks stands cluster on the permissive side of a line, and a hospital twenty minutes down the road can operate under a different state's licensing rules. A few counties take the arrangement to an extreme. Cimarron County, at the far western tip of the Oklahoma Panhandle, is the only county in the United States that touches four other states. A smaller group holds a state line and an international boundary at once, or a state line and the edge of a federal district. These are the counties where the line on the map does the most work.

Cimarron County Breaking Records

Cimarron County occupies the far western end of the Oklahoma Panhandle, and its boundaries are unmatched anywhere else in the country. The county touches New Mexico, Texas, Colorado, and Kansas, which makes it the only county in the United States that borders four other states. The Oklahoma Historical Society frames it slightly differently, citing Cimarron as the only county touching counties in five states, its own included.

The rest of the county lives up to the shape of its edges. Black Mesa, in the northwestern corner, reaches 4,973 feet and is the highest point in Oklahoma. Kenton, the small community beneath it, unofficially observes Mountain Time, an informal accommodation to sitting closer to New Mexico than to almost anything in Oklahoma. Paleontologists have worked dinosaur quarries in that same corner for decades. The 2020 census counted 2,296 residents across roughly 1,835 square miles, the smallest population of any county in the state.

Double Borders in Imperial, Yuma, Kittson, and Pembina Counties

Some counties sit on a state line. Others sit on a national boundary. A small group does both at the same time, which is where the phrase "border county" carries two meanings at once. Imperial County holds the southeastern corner of California. Riverside County lies to its north and San Diego County to its west, while the Colorado River separates it from Yuma and La Paz counties in Arizona. Its southern edge is the international boundary with Mexico. Yuma County has the same double arrangement, with California across the river to its west and the Mexican state of Sonora along its southern line.

Kittson and Pembina counties do the same thing at the opposite corner of the country, in the Red River Valley rather than anywhere near the Great Lakes. Kittson County occupies the northwestern corner of Minnesota, and Pembina County lies directly across the Red River of the North in North Dakota. Both counties reach the 49th parallel, which places the Canadian province of Manitoba along their northern edge.

Idaho's Boundary County states the arrangement in its name. It borders Washington to the west and Montana to the east, and its northern line is the boundary with British Columbia. Farther east, the double-border label gets harder to apply because much of the Canadian boundary through the Great Lakes falls on water rather than land. Along the southern edge of the country, the state line eventually meets open ocean instead of another jurisdiction.

San Juan County and Its Many Neighbors

San Juan County covers about 7,820 square miles of southeastern Utah, making it the largest county in the state. Its southeastern corner is Utah's share of the Four Corners, the single point where the boundaries of Utah, Colorado, Arizona, and New Mexico converge. It is the only place in the country where a person can stand in four states at once, and the photograph proving it has become the standard souvenir.

The Four Corners is not the county's only distinction along these lines. Counts vary depending on how single-point contacts are treated, but San Juan borders roughly fourteen other counties, more than any other county in the United States, and five of those neighbors are in Colorado. The Utah-Colorado line was surveyed with small jogs in it, so several of those contacts amount to one corner meeting another rather than a shared stretch of boundary. The county's contact with New Mexico is the narrowest of all. Utah's San Juan County meets exactly one New Mexico county, at the Four Corners point itself, and that county is also named San Juan.

The DC Border County Question

Montgomery County, Maryland, follows the north bank of the Potomac River across from Fairfax and Arlington counties in Virginia. Maryland's boundary extends to the Virginia shoreline rather than to midstream, so the state line sits at the far bank, and Montgomery is a border county in the ordinary sense. Its southeastern edge is something else: the line with Washington, DC.

The District is not a state. It is a federal district, which leaves the jurisdictions along its edge in a category without a clean name. Four county-level jurisdictions touch it. On the Maryland side, Montgomery County covers the northwest and Prince George's County the east. On the Virginia side, Arlington County lies across the river to the south, and Alexandria, an independent city that the Census Bureau counts as a county equivalent, lies to the west. Fairfax County is frequently added to that list by mistake. It is one step removed, with Arlington and Alexandria standing between it and the District.

Statehood for the District has been debated for decades and remains unresolved, so the terminology stays unsettled too. What is not in doubt is the geography. Montgomery County carries a state line along one edge and a federal district line along another, and Prince George's County does the same.

Sussex County At The Tri-State Point

Sussex County is New Jersey's northernmost county, and its upper corner is a genuine tri-state point. A monument just outside Port Jervis marks where the New Jersey boundary meets New York and Pennsylvania. The Delaware River forms the county's western line, with Pike County, Pennsylvania, on the far bank, while Orange County, New York, lies along the north.

Census geography places Sussex County inside the New York metropolitan area, a designation that undersells how rural it is. The Appalachian Trail runs along the Kittatinny Ridge through the county, and High Point, at 1,803 feet, is the highest ground in New Jersey. The two out-of-state neighbors could hardly be less alike. Pike County is thinly settled Pocono country. Orange County has roughly 400,000 residents, and it holds both the Woodbury Common outlet complex and the United States Military Academy at West Point.

Where The Line Still Holds

State boundaries were drawn by survey crews and acts of Congress, and the counties along them absorbed whatever those decisions produced. Cimarron County has four state neighbors because the Missouri Compromise fixed a latitude, and Texas surrendered its claim north of that line. San Juan County has more county neighbors than anywhere else because a survey wandered. Montgomery County faces a federal district because Maryland and Virginia each ceded land in 1790, and only Virginia's share was later returned. Each of these is a leftover, still legible on the map long after the argument that produced it was settled.