Oskaloosa District Court is formally known as the Mahaska District Court and is in the Eighth judicial district of Iowa. Both US 63 and SR 163 pass through Mahaska county and meet below Oskaloosa. SR on its way through the county passes through Oskaloosa.

Settlers began coming to Oskaloosa in the middle of the 1800's. The first settler in the county set up a trading post to Oskaloosa and built a home in the town when it was first laid out around 1844. At the time the town was a pioneer village with several cabins and 2 stores. However it continued to grow and around 1853 had approximately 1,000 residents. Stage coach traffic in the 1850's and 1860's and coal mining in the 1870's contributed to the growing economy. The city is now home to William Penn university which was founded around 1873. Since the county was named for him, it is fitting that a statue of Chief Mahaska should stand in Oskaloosa’s Courthouse square, the county seat. The Oskaloosa Symphony Orchestra performs in the George Daily Community auditorium. The Oskaloosa City Park and Band Stand are the scene of the the Oskaloosa Municipal band's annual concerts each Thursday evening from June through August.