In the colonial era, wheat was sown by broadcasting, reaped by sickles, and threshed by flails. The kernels were then taken to a grist mill for grinding into flour. In 1830, it took four people and two oxen, working 10 hours a day, to produce 200 bushels. New technology greatly increased productivity in the 19th century, as sowing with drills replaced broadcasting, cradles took the place of sickles, and the cradles in turn were replaced by reapers and binders. Steam-powered threshing machines superseded flails. By 1895, in Bonanza farms in the Dakotas, it took six people and 36 horses pulling huge harvesters, working 10 hours a day, to produce 20,000 bushels. In the 1930s the gasoline powered "combine" combined reaping and threshing into one operation that took one person to operate. Production grew from 85 million bushels in 1839, 500 million in 1880, 600 million in 1900, and peaked at 1.0 billion bushels in 1915. Prices fluctuated erratically, with a downward trend in the 1890s that caused great distress in the Plains states.