The state of Illinois is divided into townships that act as a form of local government that are larger than cities, towns, or villages, but smaller than counties. Many of the Rock Island County townships formed in the late 19th century.
The history of township government in North America is expanded on at this webpage offered by Township Officials of Illinois. It also explains that Illinois townships are required by law to provide "three basic functions": assistance for those stricken with poverty, property assessment for the purposes of taxation, and road and bridge maintenance. The site notes that many townships offer other services beyond these three categories.
Rock Island County is divided into the following townships: