States Bordering Arizona: The Four Neighbors
Arizona shares land borders with four U.S. states — and an international border with Mexico to the south.
The Four Bordering States
| State |
Direction |
Border Length |
Key Border Features |
| New Mexico |
East |
~320 mi (515 km) |
Four Corners Monument (NE corner); Apache NF; I-40, US-191, US-180 crossings |
| Utah |
North |
~210 mi (340 km) |
Lake Powell / Glen Canyon NRA; Monument Valley (AZ/UT); US-160, US-163, US-89 |
| Nevada |
Northwest |
~160 mi (260 km) |
Colorado River (Lake Mead); Hoover Dam crossing (US-93); I-11 (future) |
| California |
West |
~180 mi (290 km) |
Colorado River (entire western border); I-10, I-8, US-95, CA-62/177 crossings; Yuma agriculture |
International Border
- Mexico (Sonora & Baja California): ~370 mi (600 km) — entire southern boundary
- Ports of Entry: Nogales (DeConcini/Mariposa), Lukeville, Sasabe, Naco, Douglas, San Luis (I-19, I-8, AZ-85/86)
Geographic Context
- Four Corners (NE): Only quadripoint in US — AZ, NM, UT, CO meet
- Colorado River forms ~50% of AZ's perimeter (west + south)
- No border with: Colorado (meets at point only), Texas, Oklahoma, Kansas
Why It Matters
- Water Rights: Colorado River Compact (1922) governs 7 states + Mexico — AZ's 2.8M acre-ft allocation central to its existence
- Power Grid: AZ exports electricity to CA (Palo Verde nuclear); imports from NV/UT
- Transport: I-10 (southern transcontinental), I-40 (central), I-17 (Phoenix–Flagstaff), I-19 (Tucson–Nogales)
- Ecology: Sky Islands (SE AZ) connect to NM/Sonora; Mojave (W AZ) connects to CA/NV
Arizona's four state neighbors — New Mexico, Utah, Nevada, California — plus Mexico, define its hydrology, economy, politics, and biogeography. The Colorado River is the suture and the scalpel.
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