Prominent past representatives from the 16th district have included Everett Dirksen, who went on to become the Republican leader in the United States Senate; John B. Anderson, who became the 3rd highest ranking Republican in the House and went on to run as a major independent candidate in the 1980 Presidential election; and Lynn Martin, who later served as United States Secretary of Labor.

In this time, it generally included the northwest corner of the state, extending just far enough to the east to grab its largest city, Rockford.

Due to the 2020 redistricting, this district will shift to encompass most of central Northern Illinois, including covering the majority of the Wisconsin-Illinois border.

They are partitioned by Orth Rd, Poplar Grove Rd, Woodstock Rd, McKinley Ave, Squaw Prairie Rd, Beloit Rd, Illinois Business Route 20, Kishwaukee River, Wynwood Dr, N Appleton Rd, S Appleton Rd, Illinois Highway 5, and Stone Quarry Rd.

The 11th district takes in the communities of Candlewick Lake, Capron, Argyle (shared with Winnebago County), Caledonia, and Timberlane; most of Belvidere; and part of Poplar Grove.

The 16th district takes in the communities of Cambridge, Geneseo, Orion, Atkinson, Annawan, Lynn Center, Ophiem, Alpha, Cleveland, Osco, Andover, Woodhull, Bishop Hill, Nekoma, and Hooppole.

The 16th district takes in the communities of Lexington, Le Roy, Chenoa, El Paso (shared with Woodford County), Hudson, Gridley, Anchor, Saybrook, Bellflower, Colfax, Arrowsmith, Cooksville, Ellsworth, Towanda, Downs, Heyworth, Carlock, Twin Grove, Danvers, and Stanford; northern Normal; and part of Bloomington.

The 16th district takes in the communities of Davis, Dakota, Orangeville, Winslow, Rock City, and Lake Summerset (shared with Winnebago County); northern Cedarville; and part of Lena.

They are partitioned by W Gerber Rd/W Rosenbohm Rd, W Southport Rd, BN & SF Railroad, W Southport Rd, N Townhouse Rd, W Cottonwood Rd, N McAllister Rd, W Greengold Rd, W Farmington Rd, N Kickapoo Creek Rd, Saint Mary's Cemetery, N Swords Ave, N Northcrest Dr, C & NW Railroad, Weaverridge Golf Club, W Charter Oak Rd, Illinois Highway 6, W War Memorial Dr, N Allen Rd, W Northmoor Rd, Big Hollow Creek, West Imperial Dr, West Willow Knolls Dr, North University St, Manning Park, West Teton Dr, Illinois Highway 40, North Prospect Rd, East Prospect Ln, North Montclair Ave, East Euclid Ave, North Grandview Dr, Forest Park Nature Center, Forest Park Apartments, North Galena Rd, Illinois Highway 29, and Forest Park Riverfront-Longshore.

They are partitioned by Myelle Rd, Bass Line Rd, Illinois Highway 23, Whipple Rd, Plank Rd, Swanson Rd, and Darnell Rd.

The 16th district takes in the communities of Big Foot Prairie, Alden, Harvard, Lawrence, and Chemung.

The 16th district takes in the communities of Ransom Grand Ridge, Kangley, Streator (shared with Livingston County), Leonore, Lostant, Rutland, and Dana; and part of Seneca, Marseilles, and Tonica.