Four US states share a land border with Mexico, listed here west to east:
The 4 border states, west to east
| State | Border length | Largest border city (US) | Capital |
|---|---|---|---|
| California | 140 miles | San Diego (pop. ~1.4M) | Sacramento |
| Arizona | 373 miles | Nogales / Yuma | Phoenix |
| New Mexico | 180 miles | Las Cruces | Santa Fe |
| Texas | 1,254 miles | El Paso (pop. ~700k) | Austin |
Total US-Mexico border length: 1,954 miles (3,145 km). Texas alone is responsible for 64% of it. The border follows the Rio Grande / Río Bravo for nearly the entire Texas stretch, a natural water boundary that has been the official line since the 1848 Treaty of Guadalupe Hidalgo.
The busiest crossings
- San Ysidro / Tijuana (California ↔ Baja California). The busiest land border crossing in the Western Hemisphere. On an average day about 70,000 people enter the US by vehicle and 20,000 on foot.
- El Paso / Ciudad Juárez (Texas ↔ Chihuahua). Second busiest. The two cities form a single metro of about 2.7 million.
- Laredo / Nuevo Laredo (Texas ↔ Tamaulipas). The biggest cargo crossing, about 40% of all US-Mexico trade goes through Laredo.
- Nogales (Arizona ↔ Sonora). Major produce crossing, most winter tomatoes and grapes consumed in the US transit here.
Why these 4 states?
The current border was set by two treaties: the Treaty of Guadalupe Hidalgo (1848) ended the Mexican-American War and transferred California, Nevada, Utah, most of Arizona, about half of New Mexico, and parts of Colorado and Wyoming to the US. The Gadsden Purchase (1854) finalized the bottom of New Mexico and Arizona. Texas joined the Union in 1845 and brought its existing border with Mexico (which had been a contested issue since Texan independence in 1836).
Before 1848, the US-Mexico border ran much further north, roughly along the 42nd parallel, the present northern border of California, Nevada and Utah. The seven modern states carved wholly or partly from the 1848 cession (California, Nevada, Utah, Arizona, New Mexico, Colorado and Wyoming) are sometimes called the Mexican Cession states.
Mexican states on the other side
Six Mexican states border the US, from west to east:
- Baja California, borders California
- Sonora, borders Arizona and a small slice of New Mexico
- Chihuahua, borders New Mexico and most of West Texas
- Coahuila, borders mid-Texas
- Nuevo León, borders a small slice of South Texas
- Tamaulipas, borders southeast Texas down to the Gulf of Mexico
Border constraints in the daily puzzle
"Borders Mexico" is one of the most distinctive Statedoku constraints, exactly 4 states match it. Great for narrowing down columns fast.
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