Nevada
Nevada and Arizona.
Pacific Ocean
The Pacific Ocean is the western boundry of California.
The river, Rio Uruguay, borders Uruguay's western border.
The Potomac River forms most of Maryland's western boundary.
Montana borders North Dakota and South Dakota to the east.
It ia on the eastern border of California. The western boundary of Callifornia is the Pacific Ocean,
California shares a border with:OregonNevadaArizonaIt also shares a border with Baja California, a state in Mexico.
The Colorado River forms the western boundary between Arizona and California
Arizona. All but the extreme northwestern part of the state has the Colorado River as its boundary with Nevada and California.
Bakersfield, California, is probably the largest city in the deserts of that state. It lies on the western boundary of the Mojave.