YANKTON, a S. E. county of Dakota, separated from Nebraska by the Missouri river, and intersected by the Dakota; area, about 520 sq. m.; pop. in 1870, 2,097. The Dakota Southern railroad terminates at the county seat. The river bottoms are very fertile. The chief productions in 1870 were 18,225 bushels of wheat, 8,855 of Indian corn, 15,075 of oats, 12,459 of potatoes, 7,000 lbs. of wool, 5,060 of butter, and 3,177 tons of hay. There were 348 horses, 479 milch cows, 1,315 other cattle, 965 sheep, and 288 swine. Capital, Yankton, which is also the capital of the territory.