 butte county is a county located in the u.s. state of south dakota. as of the 2010 census, the population was 10,110. its county seat is belle fourche. the county was established in the dakota territory on march 2, 1883, and given the descriptive name based on the french word for a hill.joseph nathan kane, the american counties (4th ed.), (the scarecrow press, 1983), pp68, 479 ==history== ===prehistory=== in 1975, plesiosaurus fossils dating back to the cretaceous period were discovered in butte county. these fossils were approximately 110 million years old. in the 1980s, a 90-million-year-old fossil of a clawless lobster was discovered. a tyrannosaurus rex skeleton was found in 1981. the early human history of the belle fourche river valley, and by extension, butte county, has been traced back to about 3000 bc. the first people of the area were native americans who resided on the northwestern plains of north america. the earliest known evidence of human activity in the area dates back to the middle plains archaic period of the plains indians, which lasted from about 3000 to 1500 bc. traces of tipi rings dating from this time period have been found. in 1979 and 1980, archeologists excavated a fortified and previously inhabited site located west of belle fourche that dated back to ad 1000. this site was called the smiley-evans site and had been recorded in 1959. until 1984, only 47 archaeological sites had been recorded, but after the excavation of the smiley-evans site, several investigations were undertaken. as of 1989, 199 archaeological sites have been discovered in the county. ==geography== according to the [[united states census bureau|u.s. census bureau]
1883_establishments_in_the_United_States Butte_County,_South_Dakota Populated_places_established_in_1883 South_Dakota_counties