The District centers around the town of Keller, which is located in the San Poil Valley (erroneously called Keller Valley), and was founded in 1898 by John C. Keller, a local businessman. The town was located in the area now known as the San Poil Bay (or Old Keller to the locals); at its height the town had an estimated population of 3,500 and even featured a minor league baseball team and red light district. The town was moved several times beginning in 1941 due to back watering from the Grand Coulee Dam which flooded its previous locations and is now located eighteen miles north of the Columbia River which seriously reduced its population over time. The population at the 2010 census was 234.

The town is encompassed by the Colville Indian Reservation, and has an estimated population of roughly 1,200 people mostly of Native American descent primarily members of the Sanpoil Tribe of Indians, one of the Twelve Tribes that make up the Colville Confederated Tribes and one of the few Indian Nations that was never relocated by order of the U.S. Government.
 

 The San Poil people

The Sanpoil (or San Poil) is one of 12 aboriginal Confederated Tribes of the Colville Indian Reservation. The name Sanpoil comes from the Okanagan [snpʕwílx], "gray as far as one can see". It has been folk-etymologized as coming from the French sans poil, "without fur". The Yakama people know the tribe as Hai-ai'-nlma or Ipoilq. The Sanpoil call themselves Nesilextcl'n, .n.selixtcl'n, probably meaning "Salish speaking," and N'pooh-le, a shortened form of the name. The Sanpoil had a semi-democratic system of government with various chiefs representing each community within the tribe. Heredity was not a requirement for chiefs. In later years, United States government officials began recognizing one chief at a time.

The last four officially recognized chiefs of the San Poil Tribe were Que Que Tas (b.1822-d.1905), his son Nespelem George (b. 1863-d. Jan. 29, 1929), Skolaskin, and Jim James. The mother of Que Que Tas was a woman chief who met Lewis and Clark on the great plateau when they came through on the Pacific Northwest Expedition.

Ethnogrophy
Since the 17th century the Sanpoil flourished with a large number of villages along the Sanpoil River and Nespelem River, tributaries of the Columbia River. Later, the tribe was placed on Sanpoil and Colville Reservations in Washington state. The San Poil Tribe was incorporated into the Colville Confederation by Executive Order from the President of the United States after strong recommendation from the Indian agents noting the San Poil's relatively peaceful nature toward others (especially European settlers).

The Sanpoil are considered Interior Salish Native Americans, a designation that also includes the Okanagan, Sinixt, Lakes, Wenatchee, Nespelem, Spokan, Kalispel, Pend d'Oreilles, Coeur d'Alene, and Flathead peoples.

Ross classifies Nespelem as one of the Okanagan tribes, while Winans classifies them as part of the Sanpoil. There is little cultural and linguistic difference between the San Poil and the Nespelem.

In 1905, the United States Indian Office counted 324 Sanpoil and 41 Nespelem. In 1910, the Census counted 240 and 46. In 1913, after a survey, the Office of Indian Affairs counted 202 and 43.

List of San Poil villages
 

• Enthlukaluk, about 1.5 miles (2 km) north of the mouth of the river.
• Hahsulauk, home of the Shahsulauhuwa, near Plum.
• Hulalst, home of the S-hulalstu, at Whitestone, about 8 miles (13 km) above Npuiluk.
• Hwatsam, a winter camp, about 3 miles (5 km) above Snukeilt.
• Kakamkam, on the islands in the Sanpoil River a short distance above the mouth.
• Kathlpuspusten, home of the Kathlpuspustenak, about a mile above Plum, on the opposite side of the river.
• Ketapkunulak, on the banks of the Columbia just east of the Sanpoil River.
• Naak, home of the Snaakau, about a mile below Plum but on the north side of the river.
• Nhohogus, fishing grounds of the S-hulalstu.
• Npokstian, a winter camp, about 2 miles (3 km) above Hwatsam.
• Npuiluk, home of the Snpuiluk, at the mouth of Sanpoil River, made up of the following camps:
• Snkethlkukwiliskanan, near the present landing of the Keller ferry;
• a branch of the last called by the same name, several hundred yards north of the first between the cliff and the Sanpoil River, on the west side;
• Kethltselchin, on the first bench above the Columbia, west of the Sanpoil River.
• Nthlahoitk, a winter camp of the Snpuiluk, about halfway between Skthlamchin and Naak.
• Saamthlk, home of the Saamthlk, on the opposite side of the river from Kathlpuspusten.
• Skekwilk, on the west side of Sanpoil River about a mile above the mouth.
• Snputlem, on the east bank of Sanpoil River, about 15 miles (24 km) above the mouth.
• Snukeilt, home of the Snukeiltk, on the west side of Columbia River about 2 miles (3 km) above the mouth of Spokane River.
• Tkukualkuhun, home of the Stkukualkuhunak, at Rodger's Bar just across the river from Hunters.
• Tsaktsikskin, a winter camp of the Snpuiluk, about a half mile below Naak. Wathlwathlaskin, home of the Swathlwathlaskink, 3 miles (5 km) up the river from Nthlahoitk. 

The Mount Tolman mining proposal

From 2004 to 2006 the town of Keller was the center of attention after the Colville Tribes' controversial decision to explore the possibility of opening up an open-pit molybdenum mine on Mt Tolman in the San Poil Valley. Anti-mining groups rallied around the opposition to the mine when it soon became evident that the mining project would be too much of a hazard to the population of Washington State given research that the mine contained hazardous materials such as uranium and toxic dust that, if exposed to, an already windy location could spread up to 200 miles, encompassing most of Washington State's economic farming country. The proposal to mine also included the use of acid leaching to retrieve the metals being mined and given the mountain's short distance to the Columbia River the result would have been disastrous. Other groups also claimed the mountain's spiritual connection to the Sanpoil Tribe (the name "Tolman" comes from the Sanpoil dialect, "Tulameen" meaning "Red Paint") because many of the tribe's legends and medicines are located on the mountain itself. The group that originally sent in the proposal for the mine mostly focused on the tribe's stagnant economy and the monetary value a molybdenum mine would produce due to the high demand of the substance, a claim that the mining opposition rebutted when the evidence showed that the price of molybdenum was unpredictable and the only consistent price range was when it fell between $0.50 to $1.50 between 1955 to 1982. When the issue was brought to vote by the Colville Tribes the proposal was turned down in three legislative districts, winning approval only in the Inchelium district.

Most information courtesy of Wikipedia