Oskaloosa is a city in and the county seat of Mahaska County, Iowa, United States. The population was 11,463 in the 2010 census, an increase from 10,938 in the 2000 census.

In the 1880s, over a million tons of bituminous coal was mined in the area from 38 mines. The first mine in the area was opened shortly after 1853 by Robert Seevers, who in 1853 drove a drift into a 4-foot coalbed in an exposed creek bank east of town. Initially, coal was mined entirely for local consumption, but with the arrival of the railroads, coal from the region was shipped widely. By 1887, the report of the state mine inspector listed 11 coal mines in and around Oskaloosa. The coal output of Mahaska County surpassed that of all other Iowa counties by 1895, by which time, the output had reached over a million tons per year. In 1911, coal mining was reported to be the primary industry in the region. In 1914, the Carbon Block Coal Company of Centerville produced over 100,000 tons of coal, ranking among the top 24 coal producers in the state.

en.wikipedia.org/wiki/Oskaloosa,_Iowa