New Mexico is located in the southwestern region of the United States. With a population density of 16 per square mile, New Mexico is the sixth- most sparsely inhabited U.S. state. The state's total area is 121,412 square miles (314,460 km2). The eastern border of New Mexico lies along 103° W longitude with the state of Oklahoma, and three miles (5 km) west of 103.5° W longitude with Texas. On the southern border, Texas makes up the eastern two-thirds, while the Mexican States of Chihuahua and Sonora make up the western third, with Chihuahua making up about 90% of that. The western border with Arizona runs along the 109° 03' W longitude. The 37° N latitude parallel forms the northern boundary with Colorado. The states New Mexico, Colorado, Arizona, and Utah come together at the Four Corners in the northwestern corner of New Mexico.