What Borders Washington State?

Washington State (USA) shares borders with:

International Border

• North: British Columbia, Canada (42nd parallel to Pacific). Marine boundary in Strait of Juan de Fuca, Haro Strait, Strait of Georgia.

U.S. State Borders

• East: Idaho (longitudinal line ~117°02'W, from 46°N to 49°N).
• South: Oregon (Columbia River forms most of the boundary; 46th parallel east of river).

Maritime Boundaries

• West: Pacific Ocean (territorial waters, EEZ).
• Northwest: Maritime boundary with BC (Juan de Fuca, Haro, Georgia Straits) — settled by 1846 Oregon Treaty & 1970s equidistance agreements.

Key Border Crossings (North)

• Peace Arch (I-5 / BC-99) — Blaine, WA / Surrey, BC.
• Pacific Highway (I-5 / BC-15) — commercial.
• Lynden / Aldergrove.
• Sumas / Abbotsford-Huntingdon.
• Nighthawk / Chopaka (rural).

No border with Montana, Wyoming, or Alaska.