The first people to enter the San Pedro Valley were the Clovis people who hunted mammoth here from 10,000 years ago.
The San Pedro Valley has the highest concentration of Clovis sites in North America.
Some Clovis sites of note are the Lehner Mammoth-Kill Site, the Murray Springs Clovis Site and the Naco Mammoth-Kill Site.

The hunter-gatherer, Cochise Culture next made this area home between about 5000 to 200 BC.
Followed by the more advanced Mogollon, Hohokam and Salado cultures who built permanent homes and engaged in agriculture here.
By the time the first Europeans arrived these cultures had disappeared and the San Pedro River was home to the Sobaipuri people.

The first Europeans to visit the San Pedro River may have been the parties of Cabeza de Vaca, Fray Marcos de Niza or the Coronado expedition, and while no archeological evidence as yet exists of the passing of these groups, it has been fairly firmly established that the upper San Pedro was a widely recognized and utilized leg of the "Cibola Trail."
The Jesuit priest Eusebio Kino visited the villages along the San Pedro and Babocomari Rivers in 1692 and soon after introduced the first livestock to this area (assuming Coronado's livestock did not survive/breed).

It is widely believed that by 1762 Apache depredation drove the Sobaipuri and Spanish out of the San Pedro Valley which then remained largely uninhabited until the early 1800s.
This, however, is not true as a recent study has shown.
Documents state that not all the Sobaipuri left and in the 1780s Sobaipuri were noted still living along the river.
Archaeology has confirmed additional Sobaipuri settlements along the middle San Pedro not mentioned in the documentary record throughout the 1800s.

Early American exploration of the San Pedro River, like most rivers in western North America, was driven by the pursuit of beaver pelts.
James Ohio Pattie and his father led a party of fur trappers down the Gila River and then down the San Pedro River in 1826 which was so successful that he called the San Pedro the Beaver River.
The party was attacked by Apache Indians (probably the Aravaipa Band) at "Battle Hill" (probably Modern-day Malpais Hill) where they subsequently stashed and lost over 200 beaver pelts.
 
The Mormon Battalion marched through the river valley in 1846, and the only battle the battalion fought in their journey to California occurred near the river.
The battalion's presence had aroused curiosity among a number of wild cattle, and the bulls of these herds damaged wagons and injured mules.
In response, the men shot dozens of the charging bulls.
Mormon settlers later returned to this area in 1877 to found a settlement that became St. David, and logged the Huachuca Mountains to provide lumber for building Fort Huachuca and Tombstone.

In the 19th century the river was a meandering stream with fluvial marshlands, riparian forest, Sporobolus grasslands and extensive beaver ponds.
As the region experienced a rapid climate warming and drying, (coincident with beaver removal and large-scale cattle introduction; correlation not directly established) the river down-cut and then widened in a process of arroyo formation observed on many rivers in the Southwest.
In 1895, J. A. Allen described a mammal collection from southeastern Arizona, "On the headwaters of the San Pedro, in Sonora, a colony of a dozen or more had their lodges up to 1893, when a trapper nearly exterminated them.
All the streams in the White Mountains have beaver dams in them, although most of the animals have been trapped."
The beaver were finally extirpated by 1920s dynamiting of the beaver dams from soldiers from Fort Huachuca to prevent malaria.
By the mid-20th century the once perennial river only flowed during the rainy season and beaver, fluvial marshlands and Sporobolus grasslands were uncommon.
Physician naturalist Edgar Alexander Mearns' 1907 Mammals of the Mexican boundary of the United States reported beaver (Castor canadensis) on the San Pedro River and the Babocomari River.
Mearns claimed that the San Pedro River beaver represent
The first people to enter the San Pedro Valley were the Clovis people who hunted mammoth here from 10,000 years ago. The San Pedro Valley has the highest concentration of Clovis sites in North America. Some Clovis sites of note are the Lehner Mammoth-Kill Site, the Murray Springs Clovis Site and the Naco Mammoth-Kill Site.
The hunter-gatherer, Cochise Culture next made this area home between about 5000 to 200 BC. Followed by the more advanced Mogollon, Hohokam and Salado cultures who built permanent homes and engaged in agriculture here. By the time the first Europeans arrived these cultures had disappeared and the San Pedro River was home to the Sobaipuri people.
The first Europeans to visit the San Pedro River may have been the parties of Cabeza de Vaca, Fray Marcos de Niza or the Coronado expedition, and while no archeological evidence as yet exists of the passing of these groups, it has been fairly firmly established that the upper San Pedro was a widely recognized and utilized leg of the "Cibola Trail." The Jesuit priest Eusebio Kino visited the villages along the San Pedro and Babocomari Rivers in 1692 and soon after introduced the first livestock to this area (assuming Coronado's livestock did not survive/breed).
It is widely believed that by 1762 Apache depredation drove the Sobaipuri and Spanish out of the San Pedro Valley which then remained largely uninhabited until the early 1800s. This, however, is not true as a recent study has shown. Documents state that not all the Sobaipuri left and in the 1780s Sobaipuri were noted still living along the river. Archaeology has confirmed additional Sobaipuri settlements along the middle San Pedro not mentioned in the documentary record throughout the 1800s.
Early American exploration of the San Pedro River, like most rivers in western North America, was driven by the pursuit of beaver pelts. James Ohio Pattie and his father led a party of fur trappers down the Gila River and then down the San Pedro River in 1826 which was so successful that he called the San Pedro the Beaver River. The party was attacked by Apache Indians (probably the Aravaipa Band) at "Battle Hill" (probably Modern-day Malpais Hill) where they subsequently stashed and lost over 200 beaver pelts.  
The Mormon Battalion marched through the river valley in 1846, and the only battle the battalion fought in their journey to California occurred near the river. The battalion's presence had aroused curiosity among a number of wild cattle, and the bulls of these herds damaged wagons and injured mules. In response, the men shot dozens of the charging bulls. Mormon settlers later returned to this area in 1877 to found a settlement that became St. David, and logged the Huachuca Mountains to provide lumber for building Fort Huachuca and Tombstone.
In the 19th century the river was a meandering stream with fluvial marshlands, riparian forest, Sporobolus grasslands and extensive beaver ponds. As the region experienced a rapid climate warming and drying, (coincident with beaver removal and large-scale cattle introduction; correlation not directly established) the river down-cut and then widened in a process of arroyo formation observed on many rivers in the Southwest. In 1895, J. A. Allen described a mammal collection from southeastern Arizona, "On the headwaters of the San Pedro, in Sonora, a colony of a dozen or more had their lodges up to 1893, when a trapper nearly exterminated them. All the streams in the White Mountains have beaver dams in them, although most of the animals have been trapped." The beaver were finally extirpated by 1920s dynamiting of the beaver dams from soldiers from Fort Huachuca to prevent malaria. By the mid-20th century the once perennial river only flowed during the rainy season and beaver, fluvial marshlands and Sporobolus grasslands were uncommon. Physician naturalist Edgar Alexander Mearns' 1907 Mammals of the Mexican boundary of the United States reported beaver (Castor canadensis) on the San Pedro River and the Babocomari River. Mearns claimed that the San Pedro River beaver represent
San Pedro River (Arizona)