41°52′48″N 87°37′54″W / 41.88°N 87.6316667°W / 41.88; -87.6316667
Wong, Wailin (11 August 2009). "872 to become Chicago's 3rd area code". Chicago Tribune. Retrieved 19 August 2009. https://www.chicagotribune.com/2009/08/11/its-area-code-overload/ ↩
Local calling guide: Chicago Zone 01: Calumet, IL https://localcallingguide.com/lca_exch.php?exch=047801 ↩