Evangelical Lutheran Church, Mount Olive, Illinois, c.1900 – Charles A. Walker, Editor, Public domain – Wikimedia Commons Mount Olive is located in Macoupin County. About 2,015 people live here (as of 2020). Between 2010 and 2020, the population declined from 2,099 to 2,015. The region is at 209 meters above sea level. The area covers about 3.0 square kilometers. There are about 119 streets in Mount Olive. The postal codes are 62069. The dialing code is 618. Mount Olive is city in Illinois. Among other things, Mount Olive has schools.