New Mexico (Spanish: Nuevo México [ˈnweβo ˈmexiko] ; Navajo: Yootó Hahoodzo Navajo pronunciation: [jòːtʰó hɑ̀hòːtsò]) is a state in the Southwestern region of the United States. It is one of the Mountain States of the southern Rocky Mountains, sharing the Four Corners region with Utah, Colorado, and Arizona. It also borders the state of Texas to the east and southeast, Oklahoma to the northeast, and shares an international border with the Mexican states of Chihuahua and Sonora to the south. New Mexico's largest city is Albuquerque, and its state capital is Santa Fe, the oldest state capital in the U.S., founded in 1610 as the government seat of Nuevo México in New Spain.

New Mexico is the fifth-largest of the fifty states by area, but with just over 2.1 million residents, ranks 36th in population and 45th in population density. Its climate and geography are highly varied, ranging from forested mountains to sparse deserts; the northern and eastern regions exhibit a colder alpine climate, while the west and south are warmer and more arid. The Rio Grande and its fertile valley runs from north-to-south, creating a riparian climate through the center of the state that supports a bosque habitat and distinct Albuquerque Basin climate. One-third of New Mexico's land is federally owned, and the state hosts many protected wilderness areas and national monuments, including three UNESCO World Heritage Sites, the most of any U.S. state.

New Mexico's economy is highly diversified, including cattle ranching, agriculture, lumber, scientific and technological research, tourism, and the arts; major sectors include mining, oil and gas, aerospace, media, and film. Its total gross domestic product (GDP) in 2020 was $95.73 billion, with a GDP per capita of roughly $46,300. State tax policy is characterized by low to moderate taxation of resident personal income by national standards, with tax credits, exemptions, and special considerations for military personnel and favorable industries. New Mexico has a significant U.S. military presence, including White Sands Missile Range, and strategically valuable federal research centers, such as the Sandia and Los Alamos National Laboratories. The state hosted several key facilities of the Manhattan Project, which developed the world's first atomic bomb, and was the site of the first nuclear test, Trinity.

In prehistoric times, New Mexico was home to Ancestral Puebloans, the Mogollon culture, and ancestral Ute. Navajos and Apaches arrived in the late 15th century and the Comanches in the early 18th century. The Pueblo peoples occupied several dozen villages, primarily in the Rio Grande valley of northern New Mexico. Spanish explorers and settlers arrived in the 16th century from present-day Mexico. Isolated by its rugged terrain, New Mexico was a peripheral part of the viceroyalty of New Spain dominated by Comancheria. Following Mexican independence in 1821, it became an autonomous region of Mexico, albeit increasingly threatened by the centralizing policies of the Mexican government, culminating in the Revolt of 1837; at the same time, the region became more economically dependent on the U.S. Following the Mexican–American War in 1848, the U.S. annexed New Mexico as part of the larger New Mexico Territory. It played a central role in U.S. westward expansion and was admitted to the Union as the 47th state on January 6, 1912.

New Mexico's history has contributed to its unique demographic and cultural character. It is one of only seven majority-minority states, with the nation's highest percentage of Hispanic and Latino Americans and the second-highest percentage of Native Americans, after Alaska. The state is home to one–third of the Navajo Nation, 19 federally recognized Pueblo communities, and three federally recognized Apache tribes. Its large Hispanic population includes Hispanos descended from settlers during the Spanish era, and later groups of Mexican Americans since the 19th century. The New Mexican flag, which is among the most recognizable in the U.S., reflects the state's eclectic origins, featuring the ancient sun symbol of the Zia, a Puebloan tribe, with the scarlet and gold coloration of the Spanish flag. The confluence of indigenous, Hispanic (Spanish and Mexican), and American influences is also evident in New Mexico's unique cuisine, music genre, and architectural styles.