Southern Arizona

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Southern Arizona is the area of Arizona south of the Gila River, roughly corresponding to the area from the 1854 Gadsden Purchase (shown on the map in yellow with present-day state boundaries and cities) Gadsden Purchase Cities ZP.svg
Southern Arizona is the area of Arizona south of the Gila River, roughly corresponding to the area from the 1854 Gadsden Purchase (shown on the map in yellow with present-day state boundaries and cities)

Southern Arizona is a region of the United States comprising the southernmost portion of the State of Arizona. It sometimes goes by the name Gadsden or Baja Arizona, which means "Lower Arizona" in Spanish.

United States Federal republic in North America

The United States of America (USA), commonly known as the United States or America, is a country comprising 50 states, a federal district, five major self-governing territories, and various possessions. At 3.8 million square miles, the United States is the world's third or fourth largest country by total area and is slightly smaller than the entire continent of Europe's 3.9 million square miles. With a population of over 327 million people, the U.S. is the third most populous country. The capital is Washington, D.C., and the largest city by population is New York City. Forty-eight states and the capital's federal district are contiguous in North America between Canada and Mexico. The State of Alaska is in the northwest corner of North America, bordered by Canada to the east and across the Bering Strait from Russia to the west. The State of Hawaii is an archipelago in the mid-Pacific Ocean. The U.S. territories are scattered about the Pacific Ocean and the Caribbean Sea, stretching across nine official time zones. The extremely diverse geography, climate, and wildlife of the United States make it one of the world's 17 megadiverse countries.



The Gila River is generally considered the northern boundary of southern Arizona Gila River behind Coolidge Dam1.jpg
The Gila River is generally considered the northern boundary of southern Arizona

Although Southern Arizona's boundaries are not well-defined, it is generally considered to include all areas south of the Gila River but sometimes only Cochise County, Pima County and Santa Cruz County, anchored by the city of Tucson. Other cities and large towns in Southern Arizona include Ajo, Casa Grande, Gila Bend, Oro Valley, Sierra Vista, Yuma, and the border cities of Nogales and Douglas

Gila River river in the United States of America

The Gila River is a 649-mile (1,044 km) tributary of the Colorado River flowing through New Mexico and Arizona in the United States. The river drains an arid watershed of nearly 60,000 square miles (160,000 km2) that lies mainly within the U.S. but also extends into northern Sonora, Mexico. Indigenous peoples have lived along the river for at least 2,000 years, establishing complex agricultural societies before European exploration of the region began in the 16th century. However, European Americans did not permanently settle the Gila River watershed until the mid-19th century.

Cochise County, Arizona County in the Arizona, United States

Cochise County is located in the southeastern corner of the U.S. state of Arizona. The population was 131,346 at the 2010 census. The county seat is Bisbee.

Pima County, Arizona County in the United States

Pima County is a county in the south central region of the U.S. state of Arizona. As of the 2010 census, the population was 980,263, making it Arizona's second-most populous county. The county seat is Tucson, where nearly all of the population is centered. The county is named after the Pima Native Americans who are indigenous to this area.

Furthermore, the populated areas of Southern Arizona include the major U.S. Army post of Fort Huachuca and Davis–Monthan Air Force Base of the U.S. Air Force.

Fort Huachuca US Army base

Fort Huachuca is a United States Army installation, established 3 March 1877 as Camp Huachuca. The garrison is now under the command of the United States Army Installation Management Command. It is located in Cochise County, in southeast Arizona, about 15 miles (24 km) north of the border with Mexico and at the northern end of the Huachuca Mountains, next to the town of Sierra Vista. From 1913 to 1933 the fort was the base for the "Buffalo Soldiers" of the 10th Cavalry Regiment. During the buildup of World War II, the fort had quarters for more than 25,000 male soldiers and hundreds of WACs. In the 2010 census, Fort Huachuca had a population of about 6,500 active duty soldiers, 7,400 military family members and 5,000 civilian employees. Fort Huachuca has over 18,000 people on post during the peak working hours of 0700 and 1600 on week days, making it one of the busiest Army installations.

Davis–Monthan Air Force Base military air base near Tucson, Arizona, USA

Davis–Monthan Air Force Base is a United States Air Force base 5 miles south-southeast of downtown Tucson, Arizona. It was established in 1925 as Davis-Monthan Landing Field. The host unit for Davis–Monthan AFB is the 355th Wing assigned to Twelfth Air Force (12AF), part of Air Combat Command (ACC). The base is best known as the location of the Air Force Materiel Command's 309th Aerospace Maintenance and Regeneration Group, the aircraft boneyard for all excess military and U.S. government aircraft and aerospace vehicles.

The most major scientific site of Southern Arizona is the set of several astronomical observatories of the Kitt Peak National Observatory, a reasonable distance west-southwest of Tucson.

Kitt Peak National Observatory United States astronomical observatory

The Kitt Peak National Observatory (KPNO) is a United States astronomical observatory located on Kitt Peak of the Quinlan Mountains in the Arizona-Sonoran Desert on the Tohono O'odham Nation, 88 kilometers (55 mi) west-southwest of Tucson, Arizona. With 22 optical and two radio telescopes, it is the largest, most diverse gathering of astronomical instruments in the northern hemisphere. The observatory is administered by the National Optical Astronomy Observatory (NOAO).

Southern Arizona is the location of several large national monuments protecting the scenery, wildlife, and archaeological sites of Southern Arizona, and the Saguaro National Park, which stands on two large sections of land, one west of the Tucson metropolitan area and the other one east of Tucson.

National monument (United States) monuments assigned protected status by Presidents of the US

In the United States, a national monument is a protected area that is similar to a national park, but can be created from any land owned or controlled by the federal government by proclamation of the President of the United States.

Archaeological site Place in which evidence of past activity is preserved

An archaeological site is a place in which evidence of past activity is preserved, and which has been, or may be, investigated using the discipline of archaeology and represents a part of the archaeological record. Sites may range from those with few or no remains visible above ground, to buildings and other structures still in use.

Saguaro National Park United States National Park, in the state of Arizona

Saguaro National Park is an American national park in Pima County, southeastern Arizona. The 92,000-acre (37,000 ha) park consists of two separate areas—the Tucson Mountain District (TMD) about 10 miles (16 km) west of the city of Tucson and the Rincon Mountain District (RMD) about 10 miles (16 km) east of the city—that preserve Sonoran Desert landscapes, fauna, and flora, including the giant saguaro cactus.

Sometimes, Southern Arizona is considered to include the Phoenix Metropolitan Area, also. To some authorities, the northern boundary of Southern Arizona can be considered to be the Gila River, which sometimes flows west to the Colorado River, downstream of the ScottsdalePhoenix metropolis.

Colorado River major river in the western United States and Mexico

The Colorado River is one of the principal rivers in the Southwestern United States and northern Mexico. The 1,450-mile-long (2,330 km) river drains an expansive, arid watershed that encompasses parts of seven U.S. and two Mexican states. Starting in the central Rocky Mountains of Colorado, the river flows generally southwest across the Colorado Plateau and through the Grand Canyon before reaching Lake Mead on the Arizona–Nevada border, where it turns south toward the international border. After entering Mexico, the Colorado approaches the mostly dry Colorado River Delta at the tip of the Gulf of California between Baja California and Sonora.

Scottsdale, Arizona City in Arizona, United States

Scottsdale is a city in the eastern part of Maricopa County, Arizona, United States, part of the Greater Phoenix Area. Named Scottsdale in 1894 after its founder Winfield Scott, a retired U.S. Army chaplain, the city was incorporated in 1951 with a population of 2,000. The 2015 population of the city was estimated to be 236,839 according to the U.S. Census Bureau. The New York Times described downtown Scottsdale as "a desert version of Miami's South Beach" and as having "plenty of late night partying and a buzzing hotel scene." Its slogan is "The West's Most Western Town."

Phoenix, Arizona State capital city in Arizona, United States

Phoenix is the capital and most populous city of Arizona, with 1,660,272 people. It is also the fifth most populous city in the United States, and the most populous American state capital, and the only state capital with a population of more than one million residents.

The region includes several small mountain ranges including the Chiricahua Mountains, Huachuca Mountains, Santa Ritas, the Santa Catalinas, the Rincons, the Piñalenos, and others. As surprising as it might seem, some of these mountains are high enough, cold enough, and wet enough in the wintertime to provide alpine skiing at regular ski resorts, with ski lifts, not very distant from cities such as Tucson.


Significant distances requiring transportation in Southern Arizona are generally traveled by highway and the railroad. Southern Arizona is the location of the major transcontinental Interstate highway Interstate 10 from the border with New Mexico westward through Tucson, and then continuing northwest via Casa Grande to the Phoenix–Scottsdale–Mesa metropolis. Also, running westward from Casa Grande is Interstate 8, which goes via Yuma into California, crossing the Colorado River. Finally, the short Interstate 19 runs south from Tucson to Nogales, Arizona, and a major border crossing into Mexico. In addition, the much older Federal highway, U.S. Route 80, crosses Southern Arizona from east to west from the New Mexico border, nearly to the California border, and formerly into California to the Pacific Ocean. However, its westernmost stretch has been replaced by Interstate 8, which was built on top of it and its right-of-way.

A Transcontinental Railroad crosses Southern Arizona via Tucson and Phoenix. Also, there is a major railroad south from Northern Arizona, via Phoenix, Casa Grande, and Tucson, to Nogales, where it crosses the border and meets the Mexican railroads.

As for airline transportation, the primary major airport of Southern Arizona is located in Tucson, but also includes the larger Sky Harbor International Airport, just south of Phoenix.


Stone Avenue in the year 1880 in Tucson, southern Arizona's largest city Tucson Stone Ave year 1880.jpg
Stone Avenue in the year 1880 in Tucson, southern Arizona's largest city

Southern Arizona has been inhabited by human beings for several millennia. The Hohokam were the principal Pre-Columbian inhabitants of the area. In more recent times, the dominant indigenous group of Native Americans have been the O'odham tribe, which continues to reside in this area in their traditional homeland.

Several Spanish missions were established in the early 18th century by Father Eusebio Francisco Kino in what was then known as the Pimería Alta. After the Mexican–American War of 1846–47, much of Southern Arizona was purchased by the United States from Mexico for $15,000,000 in the Gadsden Purchase of 1854.

More recently, Southern Arizona played an important role during the Cold War. Davis-Monthan AFB was the home base of an air force wing of 18 heavy Titan II Intercontinental Ballistic Missiles dispersed over a wide area of launch sites – south, southwest, and southeast of Tucson. About 20 years ago,[ when? ] due to their advancing age and the advent of several important Strategic Nuclear Weapons Reduction treaties, all of these missiles were retired from service. All but one of their launch silos and command shelters were demolished with explosives. The remaining site, Titan II ICBM Site 571-7, about 15 miles south of Tucson on Interstate 19, serves as the Titan Missile Museum, a National Historic Landmark.


As of 2013, secession of any kind has little support anywhere in Arizona, with no ballot initiatives being generated. Beginning in 1987, a group of southern Arizonans have considered seceding from the rest of Arizona to form a new U.S. state, potentially named Gadsden. A political push to that effect began in February, 2011, led by a group of attorneys largely in opposition to what they perceived as a nativist, conservative dominance in the Phoenix area in contrast to the Democrats of the south. The organizers of this movement had aimed to hold a referendum vote on the matter in 2012 in Pima County (and, possibly, Santa Cruz County and Cochise County). [1] [2] [3]

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Interstate 19 (I-19) is a north–south Interstate Highway located entirely within the U.S. state of Arizona. I-19 travels from Nogales, roughly 300 feet (91 m) from the Mexican border, to Tucson, at I-10. The highway also travels through the cities of Rio Rico, Green Valley, and Sahuarita.

Sierra Vista, Arizona City in Arizona, United States

Sierra Vista is a city in Cochise County, Arizona, United States. As of the 2010 census the population of the city was 43,888. The city is part of the Sierra Vista-Douglas Metropolitan Area, with a 2010 population of 131,346. Fort Huachuca, a U.S. Army post, is located in the northwest part of the city.

Nogales, Arizona City in Arizona, United States

Nogales is a city in Santa Cruz County, Arizona. The population was 20,837 at the 2010 census and estimated 20,407 in 2014. Nogales forms part of the larger Tucson-Nogales combined statistical area, with a total population of 1,027,683 as of the 2010 Census. The city is the county seat of Santa Cruz County.

Gadsden Purchase A land purchase from Mexico by the United States.

The Gadsden Purchase, known in Mexico as Spanish: Venta de La Mesilla, is a 29,670-square-mile (76,800 km2) region of present-day southern Arizona and southwestern New Mexico that the United States acquired from Mexico by the Treaty of Mesilla, which took effect on June 8, 1854. The purchase included lands south of the Gila River and west of the Rio Grande which the U.S. needed to build a transcontinental railroad along a deep southern route, which the Southern Pacific Railroad later completed in 1881–1883. The purchase also aimed to resolve other border issues.

James Gadsden American diplomat, soldier, planter, politician and railroad manager

James Gadsden was an American diplomat, soldier and businessman for whom is named the Gadsden Purchase, land which the United States bought from Mexico and which became the southern portions of Arizona and New Mexico. James Gadsden served as Adjutant General of the U. S. Army from August 13, 1821 – March 22, 1822. Between 1853 and 1856, he served as U. S. Minister to Mexico. He was known commonly as General Gadsden, although he never had a rank above Colonel.

The CANAMEX corridor is a series of improvements to freeways and other transportation infrastructure linking Canada to Mexico through the United States. The corridor was established under the North American Free Trade Agreement. Currently the corridor is defined by a series of highways. However, the corridor is also proposed for use by railroads and fiber optic telecommunications infrastructure.

Santa Cruz River (Arizona) river in the United States of America

The Santa Cruz River is a river in Southern Arizona and northern Sonora, Mexico. It is approximately 184 miles (296 km) long.

Area code 520 area codes in the United States

North American area code 520 is a state of Arizona telephone area code serving Tucson and most of the southeastern part of the state.

In the U.S. state of Arizona, Interstate 10 (I‑10), the major east–west Interstate Highway in the United States Sun Belt, runs east from California, enters Arizona near the town of Ehrenberg and continues through Phoenix and Tucson and exits at the border with New Mexico near San Simon. The highway also runs through the cities of Casa Grande, Eloy, and Marana. Segments of the highway are referred to as either the Papago Freeway, Inner Loop, or Maricopa Freeway within the Phoenix area, and the Pearl Harbor Memorial Highway outside metro Phoenix.

State Route 84, also known as SR 84, is a 23-mile (37 km) east–west highway in south-central Arizona, with its western terminus at Exit 151 of Interstate 8 and its eastern terminus at its junction with State Route 387 and State Route 287 in Casa Grande. An orphaned and unsigned section runs along the final 0.87 miles (1.40 km) of State Route 87 just north of Interstate 10 near Picacho. Formerly, SR 84 ran between Tucson and Gila Bend, serving as the primary route for travelers to San Diego, California and bypassing U.S. Route 80 through Phoenix. SR 84 was also part of the Broadway of America transcontinental highway in the mid-20th Century. It was mostly replaced by both I-10 and I-8 in the late 1960s and early 1970s.

Arizona State Route 93, abbreviated SR 93, was a state highway in Arizona that existed from 1946 to 1991. The route was co-signed with other highways along nearly all of its route from Kingman to the border at Nogales. SR 93 was the original designation for the highway from Kingman to Wickenburg, which was built in 1946. In 1965, the northern terminus of the state route was moved south to an unnamed desert junction with U.S. Route 89 just north of Wickenburg, and the southern terminus of U.S. Route 93 was moved south to the US 89 junction. The Arizona Highway Department sought U.S. Highway status for SR 93 across the rest of the state, but the proposal was never granted by AASHTO. On December 17, 1984, the SR 93 designation was removed south of the Grand Avenue/Van Buren Street/7th Avenue intersection in Phoenix. The route was completely decommissioned in 1991.

The transportation system of Arizona comprises rail, air, bus, car and bicycle transport.

Traditional Arizona

Prior to the adoption of its name for a U.S. state, Arizona was traditionally defined as the region south of the Gila River to the present-day Mexican border, and between the Colorado River and the Rio Grande. It encompasses present-day Southern Arizona and the New Mexico Bootheel plus adjacent parts of Southwestern New Mexico. This area was transferred from Mexico to the United States in the Gadsden Purchase of 1853. Mining and ranching were the primary occupations of traditional Arizona's inhabitants, though growing citrus fruits had long been occurring in Tucson.

U.S. Route 80 also known as the Ocean-to-Ocean Highway, the Broadway of America and the Jefferson Davis Highway was a major transcontinental highway which existed in the U.S. state of Arizona from November 11, 1926, to October 6, 1989. At its peak, US 80 traveled from the California border in Yuma to the New Mexico state line near Lordsburg. US 80 was an important highway in the development of Arizona's car culture. Like its northern counterpart, US 66, the popularity of travel along US 80 helped lead to the establishment of many unique road side businesses and attractions, including many iconic motor hotels and restaurants.

Little Rincon Mountains

The Little Rincon Mountains are a small range of mountains, lying to the east of the Rincon Mountains, at Tucson, of eastern Pima County, Arizona. The range is located in northwest Cochise County and is part of the western border of the San Pedro River and Valley, the major valley and river of western Cochise County. The river is northward flowing to meet the Gila River; its headwaters are south of the US-Mexico border in northern Sonora. A small part of the Little Rincon range's southwest lies in Pima County.

Arizona Sun Corridor Megaregion of the U.S. in Arizona, USA

The Arizona Sun Corridor, shortened Sun Corridor, is a megaregion, or megapolitan area, in the southern area of the U.S. state of Arizona. The Sun Corridor is comparable to Indiana in both size and population. It is one of the fastest growing conurbations in the country and is speculated to double its population by 2040. The largest metropolitan areas are the Phoenix metropolitan area - Valley of the Sun - and the Tucson metropolitan area. The regions' populace is nestled in the valley of a desert environment. Similar to Southern California, the urban area extends into Mexico, reaching the communities of Nogales and Agua Prieta.

The capital of the Arizona Territory was established in Prescott, but was moved to Tucson, back to Prescott, and finally to Phoenix over 25 years as political power shifted as the territory grew, developed, and stabilized. Each move was controversial.


  1. Bodfield, Rhonda; Kelly, Andrea (February 24, 2011). "Could Baja Arizona be 51st state in US?". Arizona Daily Star. Retrieved April 2, 2011.
  2. "A tale of two counties". The Economist. March 31, 2011. Retrieved April 2, 2011.
  3. "A 51st State? Some In Arizona Want A Split". NPR. 2011-04-26. Retrieved 2011-05-10.

Coordinates: 33°23′44″N112°30′20″W / 33.3955513°N 112.5055865°W / 33.3955513; -112.5055865