Fort Pierre is a city in Stanley County, South Dakota, United States.

An American-owned trading post had been operating near what became the fort since 1817, and in 2017 the city celebrated its bicentennial of continuous permanent settlement.

[6] They left a lead plate buried in a hill to claim the land for the King of France.

[7] In the 1803 Louisiana Purchase, the United States acquired this area and the remainder of France's vast territory west of the Mississippi River.

President Thomas Jefferson commissioned the Lewis and Clark Corps of Discovery Expedition in 1804 to explore the territory, especially by traveling west to the Upper Missouri and Platte rivers, in the hope of finding a water route to the Pacific Ocean.

They met with the Teton Sioux on the south side of the mouth of the Bad River on September 24–28, 1804.

In 1817 fur trader Joseph La Framboise, Jr., an agent for the American Fur Company, established Fort Tecumseh a mile to the north, on what is now La Framboise Island in the Missouri River.

In 1832, Pierre Chouteau, Jr., a major fur trader from St Louis, replaced that early facility with Fort Pierre Chouteau, a trading post and fort on the west side of the Missouri and north side of the Bad River's mouth.

Fort Pierre celebrated its Bicentennial in 2017, marking 200 years of continuous permanent settlement at the confluence of the Missouri and Bad rivers.

Fort Pierre's reading of 120 °F is tied for the highest temperature recorded in the state of South Dakota (the other occurrence of 120 °F was at Gann Valley in 1934).