Roberts County, South Dakota, long the home of the Sisseton, Wahpeton, and Cuthead Yanktonaise Sioux, became part of Deuel and Cheyenne Counties in 1862, and in 1872 Deuel extended north to the 46th parallel, 4 miles north. The Reservation, extending south to Lake Kampeska in a giant flatiron, was established in 1867. From 1873 to 1883, Grant County included the part southeast of the Reservation. In 1883 Roberts County was created and named for S. G. Roberts, a Territorial Councilman of Fargo. It was organized on Aug. 6, 1883, by Frederick Dittes, Charles Crissey, Indian Agent, and Reuben R. Hall, at the Dittes Residence, and Travare, 2 miles southwest of Browns Valley, was named county seat. In 1884 Wilmot won the election but, after losing two court actions, stole the records and was named county seat by the 1885 Legislature. In 1898 Wilmot lost an election to Sisseton, which, fearing court action, in turn stole the records and again won approval in the 1900 election. White settlement on the Reservation came in 1892, and the railroad reached Sisseton in 1893. Post offices included Sisseton Agency in 1872, Wilmot in 1881, White Rock in 1885, Corona in 1886, Summit, Sisseton, and Effington in 1892, and Rosholt, Victor, Hammer, and Claire City in 1914, when the Soo Line entered the county. Grant County, South Dakota, once included the southeastern part of present Roberts County, and this point lay on the Sisseton-Wahpeton Flatiron Reservation, which extended down to Lake Kampeska from 1867 to 1892.