Vacant:DATE_SUCCESSOR_SEATED:Not filled this term####Illinois's 4th:VACATOR:George M. O'Brien (R)####George M. O'Brien (R):REASON_FOR_CHANGE:Died July 17, 1986####Illinois's 4th:SUCCESSOR:Vacant
After O'Brien's death on July 17, 1986, the seat remained vacant for the rest of the term.