 The first coal mine in Illinois was opened on the south bank of the Big Muddy River near the present-day Route 127 Bridge.In recent years, average temperatures in the county seat of Murphysboro have ranged from a low of in January to a high of in July, although a record low of was recorded in January 1977 and a record high of was recorded in August 1930.Average monthly precipitation ranged from in January to in May.