Guerrero, state in southern Mexico, located on the Pacific Ocean southwest of Mexico City. Guerrero is one of Mexico’s poorest and most economically underdeveloped states. It is bordered inland by the states of Oaxaca on the south, by Puebla and Morelos on the east, by Michoacán on the northwest, and by the state of Mexico on the north.

The state’s topography is dominated by the Sierra Madre del Sur mountain range and is divided into two major regions, the tropical lowlands along the coast, or Costa Chica, and the Balsas region in the interior. The Balsas region is often described as the tierra caliente, or hot country. Higher altitude mountain regions are cooler and more arid. Numerous rivers flow down the Sierra Madre del Sur into the Pacific. The Balsas River crosses the entire state, from the border with Puebla in the east, to the border with Michoacán in the west. The federal government dammed the Balsas River at Del Infiernillo dam, creating one of Mexico’s largest reservoirs, which forms a large portion of the border between Michoacán and Guerrero. Located on a mountainside just above the city of Acapulco, El Veladero National Park protects a number of unique animal and tree species, as well as the water supply for the city. The state covers an area of 64,586 sq km (24,937 sq mi).

Except for Acapulco—a major urban area and coastal resort for foreign and Mexican tourists—the state is predominantly rural, with much of the central and southwestern regions largely unsettled. In addition to its tourism industry, Acapulco is the major port in southwestern Mexico and has been significant both commercially and militarily from colonial times to the present. The Fuerte (Fort) de San Diego, built in the 18th century, is considered to be an outstanding example of military architecture from the period. Other important urban areas include Iguala, a major commercial center; Chilpancingo de los Bravos, the state capital and politically influential in the 19th century; Ixtapa-Zihuatanejo, a coastal resort region in the northwest; and Taxco (Taxco de Alarcón), known internationally for its silversmiths and craft shops. The state’s population in 2008 was 3,145,656.

Until the fall of the Aztec Empire in 1521, Guerrero was the site of significant Native American civilizations. The Plan de Iguala, Mexico’s formal declaration of independence from Spain, was issued in Iguala on February 24, 1821. The state is named after Vicente Guerrero, a prominent leader in Mexico’s struggle for independence. Guerrero gained its statehood in 1849. The isolation and poverty among much of Guerrero’s rural population has led to social violence and political conflicts throughout the 19th and 20th centuries.