Illinois House of Representatives. The Illinois House of Representatives is the lower house of the Illinois General Assembly, the state legislature of the U.S. state of Illinois. The body was created by the first Illinois Constitution adopted in 1818. The House consists of 118 representatives elected from individual legislative districts for two-year terms with no limits; redistricted every 10 years, based on the 2010 U.S. census each representative represents approximately 108,734 people.