Which of the following regions does not include New Mexico?

The Midwestern United States is indeed the correct choice, as this region does not encompass New Mexico. The Midwestern United States typically consists of states located in the central part of the country, such as Ohio, Indiana, Illinois, Michigan, Wisconsin, Minnesota, Iowa, Missouri, North Dakota, South Dakota, Nebraska, and Kansas. New Mexico is located in the southwestern corner of the country, and its geographic and cultural characteristics are distinct from those of the Midwestern states.

In contrast, the other regions mentioned are associated with New Mexico. The Southwestern United States is home to New Mexico, encompassing its historical, cultural, and geographic landscape. Similarly, the Rocky Mountain states include New Mexico although it is often considered part of the broader Southwest region. The Four Corners Region is particularly notable because it is the only point in the United States where four states meet: New Mexico, Arizona, Colorado, and Utah, further emphasizing New Mexico's inclusion in these nearby regions.