Idaho Borders: States, Map & Complete Guide

Montana and Idaho are separated by a border located on Idaho's eastern edge. This boundary runs roughly north-south from British Columbia in the north to Wyoming in the south, following the Bitterroot Range of the Rocky Mountains for much of its length.

The Idaho-Montana border extends for about 545 miles, making it Idaho's longest state border. The border follows mountain ridges and passes through remote wilderness areas. Idaho counties along this border include Boundary, Bonner, Shoshone, Clearwater, Idaho, Lemhi, and Clark. On the Montana side, Lincoln, Sanders, Mineral, Missoula, Ravalli, and Beaverhead counties sit along the border.

Wyoming and Idaho are separated by a border located on Idaho's eastern edge. The boundary runs roughly north-south from Montana in the north to Utah in the south, following the Continental Divide and passing through the Teton Range.

The Idaho-Wyoming border extends for about 150 miles. The border passes through Grand Teton National Park and Yellowstone National Park, creating one of the most scenic state borders in the country. Idaho counties along this border include Clark, Fremont, Teton, Bonneville, and Caribou.

Utah and Idaho are separated by a border located on Idaho's southern edge. The state line follows the 42nd parallel north latitude, creating a straight east-west boundary.

The Idaho-Utah border extends for about 150 miles from Wyoming in the east to Nevada in the west. Idaho counties along this border include Caribou, Franklin, Oneida, and Cassia. On the Utah side, Rich, Cache, Box Elder, and parts of other counties sit along the border.

Nevada and Idaho share Idaho's shortest state border, located in the southern part of the state. This border runs roughly north-south for a very short distance where the three states of Idaho, Nevada, and Oregon meet.

The Idaho-Nevada border is only about 25 miles long, making it Idaho's shortest border with any state. Only Owyhee County in Idaho touches this border. On the Nevada side, Elko County sits along the border.

Oregon and Idaho are separated by a border located on Idaho's western edge. The Snake River forms most of this boundary, creating a natural water border for about 200 miles.

The Idaho-Oregon border extends for about 350 miles total from Nevada in the south to Washington in the north. The Snake River winds through Hells Canyon, North America's deepest river gorge, creating dramatic scenery along the border. Idaho counties along this border include Owyhee, Malheur, Washington, Adams, and Idaho County.

Washington and Idaho are separated by a border located on Idaho's northwestern edge. The boundary includes both the Snake River in the south and a land border through the Idaho Panhandle in the north.

The Idaho-Washington border extends for about 120 miles from Oregon in the south to British Columbia in the north. The Snake River forms the southern portion of this border, while a straight line forms the northern section through the panhandle. Idaho counties along this border include Nez Perce, Clearwater, Latah, Benewah, Kootenai, and Bonner.

British Columbia and Idaho are separated by a border located at the northern tip of the Idaho Panhandle. The state line follows the 49th parallel north latitude, the same line that forms much of the U.S.-Canada border across the western states.

The Idaho-British Columbia border extends for only about 45 miles from Washington in the west to Montana in the east. Only Boundary County in Idaho touches this international border. The border passes through remote forested areas and mountains.