States That Border Mexico and Canada: Full Lists, Border Lengths and Map

Four US states border Mexico: Texas, Arizona, New Mexico and California. Texas has by far the longest share, because the Rio Grande forms the entire Texas–Mexico line.

The state figures are U.S. Geological Survey numbers published by the Congressional Research Service; Arizona's total includes 19.1 miles along the Colorado River. On the Mexican side, six states touch the United States: Baja California, Sonora, Chihuahua, Coahuila, Nuevo León and Tamaulipas.

Two pairings trip up a lot of lists. Arizona touches Baja California only along a short stretch near the Colorado River, at the far western end of its border. New Mexico's Bootheel, the rectangular extension at the state's southwest corner, reaches Sonora as well as Chihuahua.

Thirteen states border Canada: Alaska, Washington, Idaho, Montana, North Dakota, Minnesota, Michigan, Ohio, Pennsylvania, New York, Vermont, New Hampshire and Maine. Eleven of them are in the contiguous United States, plus Alaska, which has the longest share of the whole boundary.

All lengths are the International Boundary Commission's land-and-water figures. Ontario borders the most states (five), followed by Quebec and British Columbia (four each).

Ohio and Pennsylvania are the two states people forget. Their boundary with Ontario runs through the middle of Lake Erie, so there is no land crossing, but the line is an international border all the same. Wisconsin, Illinois and Indiana also front the Great Lakes, yet the boundary never reaches their waters, so they do not border Canada.

No. The four Mexico border states and the thirteen Canada border states are completely separate lists. The closest any state comes is the West Coast chain: California borders Mexico and Oregon, and Oregon borders Washington and Idaho, which border Canada. Oregon itself borders neither country.

That leaves 33 states plus the District of Columbia with no land, river or lake border with Canada or Mexico. Alaska is the only state that also faces a third country: across the Bering Strait, Russia is about 55 miles from the Alaska mainland.

You will see 1,954 miles and 1,933 miles for the Mexico border, and 5,525 miles and 3,987 miles for the Canada border. They are all correct; they measure different things.

Mexico. The International Boundary and Water Commission, the binational body that maintains the line, gives 1,954 miles for the whole continental boundary: 1,255 miles along the Rio Grande from the Gulf of Mexico to El Paso, 24 miles along the Colorado River, and 675 miles overland (534 below New Mexico and Arizona, 141 below California). It excludes the maritime boundaries of 18 miles in the Pacific and 12 miles in the Gulf. The USGS state-by-state figures in the table above sum to 1,933 miles. River boundaries are long and wiggly, and small differences in how a meandering channel is measured add up over a thousand miles.

Canada. The International Boundary Commission's 5,525 miles includes Alaska. Split into its two parts:

So "how long is the Canadian border" has two honest answers: 3,987 miles if you mean the lower 48, 5,525 miles if you include Alaska. More than two-fifths of the total is water, mostly in the Great Lakes and the St. Lawrence River system.

Both borders were set by treaties over more than a century, and both are still maintained by binational commissions.

The Gadsden Treaty explains a shape on the map that puzzles people. The 1848 line left the best southern railroad route to California in Mexico, so in 1853 the United States bought the strip south of the Gila River. That is why the southern borders of Arizona and New Mexico are straight survey lines rather than rivers.

On the Mexico side, the two countries created an International Boundary Commission in 1889, made it permanent in 1900, and renamed it the International Boundary and Water Commission in the 1944 water treaty. On the Canada side, the 1908 treaty appointed one commissioner from each country, and a 1925 treaty provided for them and their successors to keep maintaining the line. Those commissions are the sources of the lengths quoted in this post.

A large part of both borders is water, which changes what "bordering" means on the ground.

• Rio Grande. The river is the boundary for all 1,255 miles between the Gulf of Mexico and El Paso, which is why the IBWC, a water commission as much as a boundary commission, maintains it.
• Great Lakes. The Canada line runs through Lakes Superior, Huron, Erie and Ontario and the rivers that join them. Michigan's 721 miles are almost entirely water; Ohio and Pennsylvania are water only.
• Northwest Angle. A small piece of Minnesota juts north across Lake of the Woods and can be reached by land only through Manitoba. It is the only part of the contiguous United States north of the 49th parallel.
• Point Roberts. The tip of a peninsula south of Vancouver lies below the 49th parallel, so it is part of Washington State but cut off from the rest of the US by land.

The IBC keeps a clear strip 20 feet (6 m) wide along the land boundary with Canada, and more than 5,500 boundary monuments mark the land line. On a map those details disappear, which is why boundary lookups near a border always come with a margin of error. Our What Country Am I In and What State Am I In tools report the distance to the nearest line for that reason.

To make your own version of the map above, start from the blank US map with state lines and shade the seventeen border states, or use Color a Map to fill them in on screen and download the result. The plain US outline map works for tracing the two borders alone.

Each border state also has its own outline map with counties, for example the Texas blank map and Montana blank map. To see which counties actually sit on the line, the county lists are a quick reference: Texas counties along the Rio Grande run from Cameron County at the Gulf to El Paso County, and Arizona counties on the line run from Yuma County to Cochise County.