The main stem of the Saline River is long and drains . The river is formed by the confluence of the South Fork and the Middle Fork east of Harrisburg. The South Fork is long and rises in northern Johnson County within the Lake of Egypt reservoir. The Middle Fork is long and rises in southwestern Hamilton County. The North Fork of the Saline River is long and joins the main stem east of Equality, having risen in central Hamilton County southeast of McLeansboro.