Colorado is a state of the Western United States encompassing most of the southern Rocky Mountains as well as the northeastern portion of the Colorado Plateau and the western edge of the Great Plains. It is the 8th most extensive and 21st most populous U. S. state. The estimated population of Colorado was 5,695,564 on July 1, 2018, an increase of 13.25% since the 2010 United States Census. The state was named for the Colorado River, which early Spanish explorers named the Río Colorado for the ruddy silt the river carried from the mountains; the Territory of Colorado was organized on February 28, 1861, on August 1, 1876, U. S. President Ulysses S. Grant signed Proclamation 230 admitting Colorado to the Union as the 38th state. Colorado is nicknamed the "Centennial State" because it became a state one century after the signing of the United States Declaration of Independence. Colorado is bordered by Wyoming to the north, Nebraska to the northeast, Kansas to the east, Oklahoma to the southeast, New Mexico to the south, Utah to the west, touches Arizona to the southwest at the Four Corners.
Colorado is noted for its vivid landscape of mountains, high plains, canyons, plateaus and desert lands. Colorado is part of the western and southwestern United States, is one of the Mountain States. Denver is most populous city of Colorado. Residents of the state are known as Coloradans, although the antiquated term "Coloradoan" is used. Colorado is notable for its diverse geography, which includes alpine mountains, high plains, deserts with huge sand dunes, deep canyons. In 1861, the United States Congress defined the boundaries of the new Territory of Colorado by lines of latitude and longitude, stretching from 37°N to 41°N latitude, from 102°02'48"W to 109°02'48"W longitude. After 158 years of government surveys, the borders of Colorado are now defined by 697 boundary markers and 697 straight boundary lines. Colorado and Utah are the only states that have their borders defined by straight boundary lines with no natural features; the southwest corner of Colorado is the Four Corners Monument at 36°59'56"N, 109°2'43"W.
This is the only place in the United States where four states meet: Colorado, New Mexico and Utah. The summit of Mount Elbert at 14,440 feet elevation in Lake County is the highest point in Colorado and the Rocky Mountains of North America. Colorado is the only U. S. state that lies above 1,000 meters elevation. The point where the Arikaree River flows out of Yuma County and into Cheyenne County, Kansas, is the lowest point in Colorado at 3,317 feet elevation; this point, which holds the distinction of being the highest low elevation point of any state, is higher than the high elevation points of 18 states and the District of Columbia. A little less than half of Colorado is flat and rolling land. East of the Rocky Mountains are the Colorado Eastern Plains of the High Plains, the section of the Great Plains within Nebraska at elevations ranging from 3,350 to 7,500 feet; the Colorado plains are prairies but include deciduous forests and canyons. Precipitation averages 15 to 25 inches annually. Eastern Colorado is presently farmland and rangeland, along with small farming villages and towns.
Corn, hay and oats are all typical crops. Most villages and towns in this region boast both a grain elevator. Irrigation water is available from subterranean sources. Surface water sources include the South Platte, the Arkansas River, a few other streams. Subterranean water is accessed through artesian wells. Heavy use of wells for irrigation caused underground water reserves to decline. Eastern Colorado hosts considerable livestock, such as hog farms. 70% of Colorado's population resides along the eastern edge of the Rocky Mountains in the Front Range Urban Corridor between Cheyenne and Pueblo, Colorado. This region is protected from prevailing storms that blow in from the Pacific Ocean region by the high Rockies in the middle of Colorado; the "Front Range" includes Denver, Fort Collins, Castle Rock, Colorado Springs, Pueblo and other townships and municipalities in between. On the other side of the Rockies, the significant population centers in Western Colorado are the cities of Grand Junction and Montrose.
The Continental Divide of the Americas extends along the crest of the Rocky Mountains. The area of Colorado to the west of the Continental Divide is called the Western Slope of Colorado. West of the Continental Divide, water flows to the southwest via the Colorado River and the Green River into the Gulf of California. Within the interior of the Rocky Mountains are several large parks which are high broad basins. In the north, on the east side of the Continental Divide is the North Park of Colorado; the North Park is drained by the North Platte River, which flows north into Nebraska. Just to the south of North Park, but on the western side of the Continental Divide, is the Middle Park of Colorado, drained by the Colorado River; the South Park of Colorado is the region of the headwaters of the South Platte River. In southmost Colorado is the large San Luis Valley, where the headwaters of the Rio Grande are located; the valley sits between the Sangre De Cristo Mountains and San Juan Mountains, consists of large desert lands that run into the mountains.
The Rio Grande drains due south into New Mexico and Texas. Across the Sangre de Cristo Range to the east of the S
The Parker Valley is located along the Lower Colorado River within the Lower Colorado River Valley region, in southwestern Arizona and southeastern California. Its natural habitats are within the Sonoran Colorado Desert ecoregions. Riparian zone habitats on the river include Mesquite Bosques; the river has supported irrigated agricultural conversion of the valley's landscape. Three major drainages of the Colorado River enter in the Parker Valley region; the Bill Williams River and Bouse Wash have confluences with the Colorado in the northern valley area, from watersheds on the east. Tyson Wash crosses the La Posa Plain and enters downstream, with its watershed east of the river in the Colorado River Indian Reservation. In California, the Vidal Valley and the Whipple Mountains border the Parker Valley on the northwest, the Palo Verde Valley on the southwest. In Arizona the Buckskin Mountains border the valley on the north, the Cactus Plain and Dome Rock Mountains border it on the east. Settlements within Parker Valley include: Parker and Poston in Arizona.
It is at the northern area of the Colorado River Indian Reservation on the Colorado River, is at the northern perimeter of the La Posa Plain. Valleys of the Lower Colorado River Valley U. S. Geological Survey Geographic Names Information System: Parker Valley Arizona Atlas & Gazetteer, DeLorme, c. 2002, p. 70
A dam is a barrier that stops or restricts the flow of water or underground streams. Reservoirs created by dams not only suppress floods but provide water for activities such as irrigation, human consumption, industrial use and navigability. Hydropower is used in conjunction with dams to generate electricity. A dam can be used to collect water or for storage of water which can be evenly distributed between locations. Dams serve the primary purpose of retaining water, while other structures such as floodgates or levees are used to manage or prevent water flow into specific land regions; the earliest known dam is the Jawa Dam in Jordan, dating to 3,000 BC. The word dam can be traced back to Middle English, before that, from Middle Dutch, as seen in the names of many old cities; the first known appearance of dam occurs in 1165. However, there is one village, mentioned in 1120; the word seems to be related to the Greek word taphos, meaning "grave" or "grave hill". So the word should be understood as "dike from dug out earth".
The names of more than 40 places from the Middle Dutch era such as Amsterdam and Rotterdam bear testimony to the use of the word in Middle Dutch at that time. Early dam building took place in the Middle East. Dams were used to control the water level, for Mesopotamia's weather affected the Tigris and Euphrates rivers; the earliest known dam is the Jawa Dam in Jordan, 100 kilometres northeast of the capital Amman. This gravity dam featured an 9-metre-high and 1 m-wide stone wall, supported by a 50 m-wide earth rampart; the structure is dated to 3000 BC. The Ancient Egyptian Sadd-el-Kafara Dam at Wadi Al-Garawi, located about 25 km south of Cairo, was 102 m long at its base and 87 m wide; the structure was built around 2800 or 2600 BC as a diversion dam for flood control, but was destroyed by heavy rain during construction or shortly afterwards. During the Twelfth Dynasty in the 19th century BC, the Pharaohs Senosert III, Amenemhat III and Amenemhat IV dug a canal 16 km long linking the Fayum Depression to the Nile in Middle Egypt.
Two dams called Ha-Uar running east-west were built to retain water during the annual flood and release it to surrounding lands. The lake called "Mer-wer" or Lake Moeris is known today as Birket Qarun. By the mid-late third millennium BC, an intricate water-management system within Dholavira in modern-day India was built; the system included 16 reservoirs and various channels for collecting water and storing it. One of the engineering wonders of the ancient world was the Great Dam of Marib in Yemen. Initiated somewhere between 1750 and 1700 BC, it was made of packed earth – triangular in cross section, 580 m in length and 4 m high – running between two groups of rocks on either side, to which it was linked by substantial stonework. Repairs were carried out during various periods, most important around 750 BC, 250 years the dam height was increased to 7 m. After the end of the Kingdom of Saba, the dam fell under the control of the Ḥimyarites who undertook further improvements, creating a structure 14 m high, with five spillway channels, two masonry-reinforced sluices, a settling pond, a 1,000 m canal to a distribution tank.
These extensive works were not finalized until 325 AD and allowed the irrigation of 25,000 acres. Eflatun Pınar is a Hittite spring temple near Konya, Turkey, it is thought to be from the time of the Hittite empire between the 15th and 13th century BC. The Kallanai is constructed of unhewn stone, over 300 m long, 4.5 m high and 20 m wide, across the main stream of the Kaveri river in Tamil Nadu, South India. The basic structure dates to the 2nd century AD and is considered one of the oldest water-diversion or water-regulator structures in the world, still in use; the purpose of the dam was to divert the waters of the Kaveri across the fertile delta region for irrigation via canals. Du Jiang Yan is the oldest surviving irrigation system in China that included a dam that directed waterflow, it was finished in 251 BC. A large earthen dam, made by Sunshu Ao, the prime minister of Chu, flooded a valley in modern-day northern Anhui province that created an enormous irrigation reservoir, a reservoir, still present today.
Roman dam construction was characterized by "the Romans' ability to plan and organize engineering construction on a grand scale." Roman planners introduced the then-novel concept of large reservoir dams which could secure a permanent water supply for urban settlements over the dry season. Their pioneering use of water-proof hydraulic mortar and Roman concrete allowed for much larger dam structures than built, such as the Lake Homs Dam the largest water barrier to that date, the Harbaqa Dam, both in Roman Syria; the highest Roman dam was the Subiaco Dam near Rome. Roman engineers made routine use of ancient standard designs like embankment dams and masonry gravity dams. Apart from that, they displayed a high degree of inventiveness, introducing most of the other basic dam designs, unknown until then; these include arch-gravity dams, arch dams, buttress dams and multiple arch buttress dams, all of which were known and employed by the 2nd century AD. Roman workforces were the first to build dam bridges, such as the Bridge of Valerian in Iran
Imperial County, California
Imperial County is a county in the U. S. state of California. As of the 2010 census, the population was 174,528; the county seat is El Centro. Established in 1907 from a division of San Diego County, it was last county to be formed in California. Imperial County includes California Metropolitan Statistical Area, it is part of the Southern California border region, the smallest but most economically diverse region in the state. It is located in the Imperial Valley, in the far southeast of California, bordering both Arizona and the Mexican state of Baja California. Although this region is a desert, with high temperatures and low average rainfall of three inches per year, the economy is based on agriculture due to irrigation, supplied wholly from the Colorado River via the All-American Canal; the Imperial Valley is divided between the United States and Mexico, Imperial County is influenced by Mexican culture. 80% of the county's population is Hispanic, with the vast majority being of Mexican origin.
The remainder of the population is predominantly non-Hispanic white as well as smaller African American, Native American and Asian minorities. In 2016, Imperial County had the highest percentage of unemployed people of any county in the United States, at 23.5%. Spanish explorer Melchor Díaz was one of the first Europeans to visit the area around Imperial Valley in 1540; the explorer Juan Bautista de Anza explored the area in 1776. Years after the Mexican–American War, the northern half of the valley was annexed by the U. S. while the southern half remained under Mexican rule. Small scale settlement in natural aquifer areas occurred in the early 19th century, but most permanent settlement was after 1900. In 1905, torrential rainfall in the American Southwest caused the Colorado River to flood, including canals, built to irrigate the Imperial Valley. Since the valley is below sea level, the waters never receded, but collected in the Salton Sink in what is now called the Salton Sea. Imperial County was formed in 1907 from the eastern portion of San Diego County.
The county took its name from Imperial Valley, itself named for the Imperial Land Company, a subsidiary of the California Development Company, which at the turn of the 20th century had claimed the southern portion of the Colorado Desert for agriculture. Much of the Imperial Land Company's land existed in Mexico; the objective of the company was commercial crop farming development. By 1910, the land company had managed to settle and develop thousands of farms on both sides of the border; the Mexican Revolution soon after disrupted the company's plans. Nearly 10,000 farmers and their families in Mexico were ethnically cleansed by the rival Mexican armies. Not until the 1920s was the other side of California in America sufficiently peaceful and prosperous for the company to earn a return for a large percentage of Mexicans, but some chose to stay and lay down roots in newly sprouted communities in the valley; the county experienced a period of migration of "Okies" from drought-trodden dust bowl farms by the need of migrant labor, prosperous job-seekers alike from across the U.
S. arrived in the 1930s and 1940s in World War II and after the completion of the All American Canal from its source, the Colorado River, from 1948 to 1951. By the 1950 census, over 50,000 residents lived in Imperial County alone, about 40 times that of 1910. Most of the population was year-round but would increase every winter by migrant laborers from Mexico; until the 1960s, the farms in Imperial County provided substantial economic returns to the company and the valley. El Centro has one of the highest unemployment rates in the U. S. and ranks one of California's poorest counties or have a lower than state and national average annual household income. Fort Yuma is located on the banks of the Colorado River in California. First established after the end of the Mexican–American War in 1848, it was located in the bottoms near the Colorado River, less than 1 mile below the mouth of the Gila River, it was to defend the newly settled community of Yuma, Arizona on the other side of the Colorado River and the nearby Mexican border.
In March 1851 the post was moved to a small elevation on the Colorado's west bank, opposite the present city of Yuma, Arizona, on the site of the former Mission Puerto de Purísima Concepción. This site had been occupied by Camp Calhoun, named for John C. Calhoun, established in 1849. Fort Yuma was established to protect the southern emigrant travel route to California and to attempt control of the Yuma Indians in the surrounding 100-mile area. NAF El Centro is the winter home of the U. S. Navy Flight Demonstration Squadron, The Blue Angels. NAF El Centro kicks off the Blue Angels' season with their first air show, traditionally held in March. Imperial, CA is home to the California Mid-Winter Fair and Fiesta, the local county fair, held in late February to early March, it is home to the Imperial Valley Speedway, a race track of 3⁄8 mile. The name Algodones Dunes refers to the entire geographic feature, while the administrative designation for that portion managed by the Bureau of Land Management is the "Imperial Sand Dunes Recreation Area".
The Algodones Sand Dunes are the largest mass of sand dunes in California. This dune system extends for more than 40 miles along the eastern edge of the Imperial Valley agricultural region in a band averaging 5 miles in width. A major east-west route of the Union Pacific railroad skirts the e
The Colorado Plateau known as the Colorado Plateau Province, is a physiographic and desert region of the Intermontane Plateaus centered on the Four Corners region of the southwestern United States. This province covers an area of 336, 700 km2 within western Colorado, northwestern New Mexico and eastern Utah, northern Arizona. About 90% of the area is drained by the Colorado River and its main tributaries: the Green, San Juan, Little Colorado. Most of the remainder of the plateau is drained by its tributaries; the Colorado Plateau is made up of high desert, with scattered areas of forests. In the southwest corner of the Colorado Plateau lies the Grand Canyon of the Colorado River. Much of the Plateau's landscape is related, in both appearance and geologic history, to the Grand Canyon; the nickname "Red Rock Country" suggests the brightly colored rock left bare to the view by dryness and erosion. Domes, fins, river narrows, natural bridges, slot canyons are only some of the additional features typical of the Plateau.
The Colorado Plateau has the greatest concentration of U. S. National Park Service units in the country outside the Washington, DC metropolitan area. Among its nine National Parks are Grand Canyon, Bryce Canyon, Capitol Reef, Arches, Mesa Verde, Petrified Forest. Among its 18 National Monuments are Bears Ears, Rainbow Bridge, Hovenweep, Sunset Crater Volcano, Grand Staircase-Escalante, Natural Bridges, Canyons of the Ancients, Chaco Culture National Historical Park and the Colorado National Monument; this province is bounded by the Rocky Mountains in Colorado, by the Uinta Mountains and Wasatch Mountains branches of the Rockies in northern and central Utah. It is bounded by the Rio Grande Rift, Mogollon Rim and the Basin and Range Province. Isolated ranges of the Southern Rocky Mountains such as the San Juan Mountains in Colorado and the La Sal Mountains in Utah intermix into the central and southern parts of the Colorado Plateau, it is composed of six sections: Uinta Basin Section High Plateaus Section Grand Canyon Section Canyon Lands Section Navajo Section Datil SectionAs the name implies, the High Plateaus Section is, on average, the highest section.
North-south trending normal faults that include the Hurricane, Grand Wash, Paunsaugunt separate the section's component plateaus. This fault pattern is caused by the tensional forces pulling apart the adjacent Basin and Range province to the west, making this section transitional. Occupying the southeast corner of the Colorado Plateau is the Datil Section. Thick sequences of mid-Tertiary to late-Cenozoic-aged lava covers this section. Development of the province has in large part been influenced by structural features in its oldest rocks. Part of the Wasatch Line and its various faults form the western edge of the province. Faults that run parallel to the Wasatch Fault that lies along the Wasatch Range form the boundaries between the plateaus in the High Plateaus Section; the Uinta Basin, Uncompahgre Uplift, the Paradox Basin were created by movement along structural weaknesses in the region's oldest rock. In Utah, the province includes several higher fault-separated plateaus: Awapa Plateau Aquarius Plateau Kaiparowits Plateau Markagunt Plateau Paunsaugunt Plateau Sevier Plateau Fishlake Plateau Pavant Plateau Gunnison Plateau and the Tavaputs Plateau.
Some sources include the Tushar Mountain Plateau as part of the Colorado Plateau, but others do not. The flat-lying sedimentary rock units that make up these plateaus are found in component plateaus that are between 4,900 to 11,000 feet above sea level. A supersequence of these rocks is exposed in the various cliffs and canyons that make up the Grand Staircase. Younger east-west trending escarpments of the Grand Staircase extend north of the Grand Canyon and are named for their color: Chocolate Cliffs, Vermillion Cliffs, White Cliffs, Gray Cliffs, the Pink Cliffs. Within these rocks are abundant mineral resources that include uranium, coal and natural gas. Study of the area's unusually clear geologic history has advanced that science. A rain shadow from the Sierra Nevada far to the west and the many ranges of the Basin and Range means that the Colorado Plateau receives six to sixteen inches of annual precipitation. Higher areas receive more precipitation and are covered in forests of pine and spruce.
Though it can be said that the Plateau centers on the Four Corners, Black Mesa in northern Arizona is much closer to the east-west, north-south midpoint of the Plateau Province. Lying southeast of Glen Canyon and southwest of Monument Valley at the north end of the Hopi Reservation, this remote coal-laden highland has about half of the Colorado Plateau's acreage north of it, half south of it, half west of it, half east of it; the Ancestral Puebloan People lived in the region from 2000 to 700 years ago. A party from Santa Fe led by Fathers Dominguez and Escalante, unsuccessfully seeking an overland route to California, made a five-month out-and-back trip through much of the Plateau in 1776-1777. Despite having lost one arm in the American Civil War, U. S. Army Major and geologist John Wesley Powell explored the area in 1869 and 1872. Using wooden oak boats and small groups of men the Powell Geographic Expedition charted this unknown region of the United States for the federal government. Construction of the Hoover Dam in the 1930s and the Glen Canyon Dam in the 1960s changed the character of the Colorado River.
Reduced sediment load changed its color from reddish brown t
The Alamo Canal was a 14 mi long waterway that connected the Colorado River to the head of the Alamo River. The canal was constructed to provide irrigation to the Imperial Valley. A small portion of the canal was located in the United States but the majority of the canal was located in Mexico; the Alamo Canal is known as the Imperial Canal. The Colorado River flowed to the Gulf of California, however in times of the spring floods the Colorado River would overflow its banks and drain into the Alamo River. Flow from the Alamo River drained to the Salton Sink area of the Colorado Desert; such overflow had been observed in 1884, 1891, 1892, 1895. In the mid- to late-Nineteenth Century several individuals, most notably O. M. Wozencraft, proposed irrigating the Salton Sink by diverting a controlled gravity-fed flow of the Colorado River through the existing dry Alamo River bed; the Alamo Canal was the first attempt to create that diversion. It was engineered by George Chaffey of the California Development Company starting in 1900.
The canal intake and temporary wooden headgates were located in the United States at Pilot Knob due to the availability of a solid rock foundation. The canal crossed the border with Mexico and ran parallel to the Colorado River for 4 miles, where a channel was cut several miles west to the head of the Alamo River; this path was selected to avoid the expensive engineering that would otherwise be required if the canal were to traverse the Algodones Dunes. A small amount of irrigation water was first delivered to the Imperial Valley in 1901, with larger flows becoming available in 1902. In 1906 work was completed on the permanent concrete headgates at Hanlon Heading. In 1904 heavy silting reduced the water-carrying capacity of the canal. Imperial Valley farmers, under considerable financial stress, pressured the California Development Company to resolve the problem. Charles Rockwood, faced with bankruptcy and "after mature deliberation", directed the engineering of a breach in the bank of the Colorado River 4 miles south of the existing wooden headgates.
The breach, known as the Lower Mexican Intake, constructed without headgates and without the permission of the Mexican authorities, allowed the Colorado River to flow unimpeded into the canal, to Imperial Valley farms. During the subsequent seasonal floods of 1904 through to late 1906, a large amount of the water carried in the Colorado River flowed directly into the Salton Sink. At various times during this period the entirety of the Colorado River was diverted into the canal. Rockwood's action in ordering the breach was described as a "blunder so serious as to be criminal."Multiple failed attempts were made to close the diversion and establish a controlled flow via headgates. On January 27, 1907, the flooding was stopped after substantial intervention by the Southern Pacific Company; the rate of water loss through aquifer replenishment and evaporation in the Salton Sink was much less than the massive inflow of the Colorado River via the third diversion of the Alamo Canal. As a direct result of the decision to create canal intakes from the Colorado River without headgates the Salton Sea was formed.
Ongoing provision of water to the Imperial Valley from the Alamo Canal ensured that the Salton Sea would remain intact through the lifetime of the canal. The initial flooding of the Salton Sink destroyed. On January 10, 1908, the owners of the works were awarded a judgement against the California Development Company of $458,246.23. Southern Pacific, which incurred considerable costs repairing the breaches, held a judgement against California Development of $3,772,128.52. By June, 1915 a total of $5,049,554.78 was owed to creditors, with most of those costs and judgements directly related to the failure of the canal. This debt triggered the bankruptcy of California Development, with all assets passed to Southern Pacific. In 1911 Imperial Valley farmers formed the Imperial Irrigation District. By 1916 the Imperial Irrigation District had purchased all the ex-California Development assets from Southern Pacific and assumed operation of the canal. Construction of the All-American Canal was completed in 1940.
By 1942 the All-American Canal was the sole canal providing Colorado River water to the Imperial Valley. Colorado River Irrigation Company Imperial Land Company Morelos Dam All-American Canal Media related to Alamo Canal at Wikimedia Commons
Sonora Estado Libre y Soberano de Sonora, is one of 31 states that, with Mexico City, comprise the 32 federal entities of United Mexican States. It is divided into 72 municipalities. Sonora is bordered by the states of Chihuahua to the east, Baja California to the northwest and Sinaloa to the south. To the north, it shares the U. S.–Mexico border with the states of Arizona and New Mexico, on the west has a significant share of the coastline of the Gulf of California. Sonora's natural geography is divided into three parts: the Sierra Madre Occidental in the east of the state, it is arid or semiarid deserts and grasslands, with only the highest elevations having sufficient rainfall to support other types of vegetation. Sonora is home to eight indigenous peoples, including the Mayo, the O’odham, the Yaqui, Seri, it has been economically important for its agriculture and mining since the colonial period, for its status as a border state since the Mexican–American War. With the Gadsden Purchase, Sonora lost more than a quarter of its territory.
From the 20th century to the present, industry and agribusiness have dominated the economy, attracting migration from other parts of Mexico. Several theories exist as to the origin of the name "Sonora". One theory states that the name was derived from Nuestra Señora, the name given to the territory when Diego de Guzmán crossed the Yaqui River on the day of Nuestra Señora del Rosario, which falls on 7 October with the pronunciation changing because none of the indigenous languages of the area have the ñ sound. Another theory states that Álvar Núñez Cabeza de Vaca and his companions, who had wrecked off the Florida coast and made their way across the continent, were forced to cross the arid state from north to south, carrying an image of Nuestra Señora de las Angustias on a cloth, they encountered the Opata, who could not pronounce Señora, instead saying Sonora. A third theory, written by Father Cristóbal de Cañas in 1730, states that the name comes from the word for a natural water well, which the Spaniards modified to "Sonora".
The first record of the name Sonora comes from explorer Francisco Vásquez de Coronado, who passed through the state in 1540 and called part of the area the Valle de la Sonora. Francisco de Ibarra traveled through the area in 1567 and referred to the Valles de Señora; the literal meaning of "sonora" in Spanish is "sonorous" or "loud." Evidence of human existence in the state dates back over 10,000 years, with some of the best-known remains at the San Dieguito Complex in the El Pinacate Desert. The first humans were nomadic hunter gatherers who used tools made from stones and wood. During much of the prehistoric period, the environmental conditions were less severe than they are today, with similar but more dense vegetation spread over a wider area; the oldest Clovis culture site in North America is believed to be El Fin del Mundo in northwestern Sonora. It was discovered during a 2007 survey, it features occupation dating around 13,390 calibrated years BP. In 2011, remains of Gomphothere were found.
Agriculture first appeared around 400 200 CE in the river valleys. Remains of ceramics have been found dating from 750 CE with diversification from 800 and 1300 CE Between 1100 and 1350, the region had complex small villages with well-developed trade networks; the lowland central coast, seems never to have adopted agriculture. Because Sonora and much of the northwest does not share many of the cultural traits of that area, it is not considered part of Mesoamerica. Though evidence exists of trade between the peoples of Sonora and Mesoamerica, Guasave in Sinaloa is the most north-westerly point considered Mesoamerican. Three archaeological cultures developed in the low, flat areas of the state near the coast: the Trincheras tradition, the Huatabampo tradition, the Central Coast tradition; the Trincheras tradition is dated to between 750 and 1450 CE and known from sites in the Altar and Concepción valleys, but its range extended from the Gulf of California into northern Sonora. The tradition is named after trenches found in a number of sites, the best known of, the Cerro de Trincheras.
The Huatabampo tradition is centered south of the Trincheras along the coast, with sites along extinct lagoons and river valleys. This tradition has a distinctive ceramic complex. Huatabampo culture shows similarities with the Chametla to the Hohokam to the north; this ended around 1000 CE. Unlike the other two traditions, the Central Coast remained a hunter-gatherer culture, as the area lacks the resources for agriculture; the higher elevations of the state were dominated by the Casas Grandes and Río Sonora tradition. The Río Sonora culture is located in central Sonora from the border area to modern Sinaloa. A beginning date for this culture has not been determined but it disappeared by the early 14th century; the Casas Grandes tradition in Sonora was an extension of the Río Sonora tradition based in the modern state of Chihuahua, which exterted its influence down to parts of the Sonoran coast. Climatic changes in the middle of the 15th century resulted in the increased desertification of northwest Mexico in general.
This is the probable cause for the drastic decrease in the number and size of settlements starting around this time. The peoples that remained in the area reverted to a less complex social organiz