Arizona. All but the extreme northwestern part of the state has the Colorado River as its boundary with Nevada and California.
The Colorado River.
The Colorado River
The Colorado River on its way to the Sea of Cortez.The Colorado River.The Colorado River, which is the same river that runs through the Grand Canyon, forms the boundary between California and Arizona.The Colorado River.
The Colorado river
It ia on the eastern border of California. The western boundary of Callifornia is the Pacific Ocean,
The Colorado River forms the western boundary between Arizona and California
The Colorado River forms part of the southwest boundary of the United States.
In 1802, the Mississippi River formed the western boundary of the United States. The southern boundary extended to the 31st parallel north latitude.
The Mississippi River forms the western boundary of the State of Illinois.
The Mississippi River
The Colorado River is a prominent river in the western region of the United States, flowing through several states including Colorado, Utah, and Arizona. One famous mountain in the western region is the Sierra Nevada, stretching along the border of California and Nevada with peaks such as Mount Whitney.
The Appalachain Mountains marked the western boundary during the French and Indian War. Afterwards, it was mainly the Mississippi River that marked the boundary.