The United States acquired the territory from British Rupert's Land with the Treaty of 1818, but indigenous tribes dominated the area until the late 19th century. After years of warfare, the United States made treaties to extinguish the land claims of the Ojibwe and other Native American peoples. When a U.S. post office was established on the site on June 15, 1870, the name was changed to the English "Grand Forks". Alexander Griggs, a steamboat captain, is regarded as "The Father of Grand Forks". Griggs' steamboat froze in the Red River on a voyage in late 1870, forcing the captain and his crew to spend the winter camping at Grand Forks. Griggs platted a community in 1875, and Grand Forks was officially incorporated on February 22, 1881.