220 Kilometers (137 miles).
The states that border Mexico are California, Arizona, New Mexico and Texas...
New Mexico shares it's long southern border with Texas.
You can step across since they share a common border,
California borders Mexico.
Mexico cession
Nothing. California borders Mexico.
Zero. Mexico and California share a border.
Texas, California, New Mexico and Arizona all border Mexico.
California's southern border is shared with the country of Mexico.
Mexico
California was acquired from Mexico at the end of the Mexican-American War (1846-1848). Since then, southern California has been part of the US-Mexico Border.
At the California/Mexico border it is a matter of inches.