Prior to the effective date of this amendatory Act of the 102nd General Assembly, the Third Judicial District consists of the counties of Mercer, Rock Island, Whiteside, Henry, Bureau, LaSalle, Grundy, Stark, Putnam, Marshall, Peoria, Tazewell, Will, Kankakee, Iroquois, Henderson, Warren, Knox, Fulton, McDonough and Hancock.