OSKALOOSA, a city of the United States, capital of Mahaska county, Iowa, about 55 miles south-east of Des Moines. It lies on high ground between the Des Moines and the South Skunk, in a fine agricultural district, with coal and iron mines in the vicinity; and it contains two colleges—Oskaloosa College (1861), belonging to the “Disciples,” and Penn College (1873), a Quaker institution—flour-mills, wool-factories, iron and brass foundries, lumber yards, &c., and an artesian well 2900 feet deep. The population, 3204 in 1870 and 4598 in 1880, is estimated at over 7000 in 1884.