The 43rd District is located mostly within Will County. Major population centers include Bonnie Brae, Braidwood, Channahon, Coal City, Crest Hill, Diamond, Elwood, Fairmont, Ingalls Park, Joliet, Lemont, Lockport, Lockport Heights, Lorenzo, Manhattan, Minooka, Naperville, Preston Heights, Ridgewood, Rockdale, Romeoville, Shorewood, Wilmington and Woodridge.

Major employers in district communities include Argonne National Laboratory, Provena St. Joseph Medical Center, Commonwealth Edison, Caterpillar's earthmoving equipment factory, Silver Cross Hospital, Harrah's casino, and several local school districts.