Which region of the United States is characterized by the Colorado River flowing through it?

The Colorado River primarily flows through the Southwest region of the United States, making it the correct answer to the question. This region encompasses parts of several states, including Arizona, Utah, Nevada, California, Colorado, and New Mexico. The river is known for its significant geographical and economic importance, including its role in providing water for agriculture and urban areas as well as shaping the landscapes of places like the Grand Canyon.

The Southwest region is also noted for its desert environments and diverse ecosystems, which are influenced by the presence of the Colorado River.

In contrast, the Great Plains are characterized by flat grassland and are not associated with significant river systems like the Colorado. The Rocky Mountains refer to the mountain range that extends from Canada down through the western United States, encompassing some areas where the Colorado River originates but not the primary regions it flows through. The Northeast is known for its historical significance and natural features different from those of the Southwest, including forests, rivers, and urban areas, but it does not include the Colorado River.