Oregon's Neighbors: The Four States Bordering the Beaver State

Oregon sits in the Pacific Northwest, bordered by four states along lines drawn by longitude, latitude, and watershed divides:

• Washington (north): 46th parallel north (mostly); Columbia River forms 300+ miles of the boundary. Shared: Portland/Vancouver metro, Columbia Gorge, Cascade volcanoes (St. Helens, Adams, Rainier visible from both).
• Idaho (east): Meridian 117°02'23"W (mostly); Snake River forms southern 200 miles (Hells Canyon—deepest gorge in North America). Shared: Blue Mountains, high desert, wheat/Potato belt.
• Nevada (southeast): 42nd parallel north (short 50-mile segment); remote basin-and-range; no major roads cross directly (US-95 cuts NV corner). Shared: Owyhee Desert, minimal interaction.
• California (south): 42nd parallel north (straight line, 300+ miles); Siskiyou Mountains, Klamath Basin. Shared: I-5 corridor (major freight), Rogue/Klamath watersheds, fire management, water wars (Klamath Project).

Maritime Border

Pacific Ocean (west): 363 miles coastline. Territorial sea (3 nm), EEZ (200 nm) shared with federal jurisdiction, not states.

Historical Notes

• Oregon Territory (1848) included Washington, Idaho, parts of Montana/Wyoming
• Washington split 1853; Idaho 1863; boundaries finalized with statehood (1859, 1889, 1890)
• 42nd parallel from 1819 Adams-Onís Treaty (US–Spain); 46th parallel from 1846 Oregon Treaty (US–UK)

Tri-State Points

• OR-WA-ID: Summit of 6,400-ft peak in Blue Mountains (no marker, wilderness)
• OR-ID-NV: Remote Owyhee Desert (BLM land)
• OR-NV-CA: Surveyed 1868; marker exists near Goose Lake

Cross-Border Integration

Portland-Vancouver (OR-WA) is a true bi-state metro (light rail, tax coordination). Ontario (OR)–Boise (ID) economic ties. Klamath Falls (OR)–Yreka (CA) medical/shopping. Nevada border: minimal.