Illinois 2 used to follow the Rock River from Rock Island to South Beloit. It was used in the 19th century as a primary trading route from Rockford to Rock Island, The Rock River was not used as a trading route for boats as it is only navigable west of Rock Falls.
Illinois 2 has since been superseded by Interstate 39 and Interstate 88 for most ground transportation, but the original route remains.
In Sterling, IL 2 begins as a one-way pair. Near the Sinnissippi Mounds, the two one-way roads merge into a two-way road. From Sterling to Dixon, IL 2 largely follows a portion of Lincoln Highway but with one exception. Lincoln Highway branches off northeast to Palmyra and then back southeast to IL 2 just northwest of Dixon. Just north of Dixon, both routes run concurrently with US 52 and IL 26. They then cross the Rock River to get to downtown. In downtown, IL 2 branches off northeast from the other two routes.
At Grand Detour, IL 2 transitions from following the south/east bank of Rock River to the north/west bank via a bridge. Further north, it passes through Castle Rock State Park, IL 64 at the Ogle County Courthouse in Oregon, and IL 72 in Byron (runs concurrently with IL 2). North of the Chicago Rockford International Airport, IL 2 turns north. At this point, it largely parallels IL 251 for the rest of the route which is east of the river. It then meets US 20 at a diamond interchange (formerly a cloverleaf interchange).
As IL 2 gets closer to downtown Rockford, another split occurs. Northbound traffic continues on Main Street, then east on Chestnut Street (US 20 Business), then north on Wyman Street, then west on Park Avenue near the site of Beattie Park Mound Group, and then back north on Main Street before merging. Southbound traffic has to turn west onto John Street, then south on Church Street, and then east on Cedar Street before merging.
In Rockton, IL 2 transitions from the west side of the river to the east side again. Further north, IL 75 runs concurrently with IL 2 from Rockton to South Beloit. One third of a mile from the Wisconsin state line, IL 75 leaves this concurrency to travel East while IL 2 continues North over a railroad grade crossing and Turtle Creek before reaching its Northern terminus at a junction with WIS 213.[4]
History
Sign located in Ogle County
SBI Route 2 originally ran from South Beloit to Cairo. It followed a part of current IL 2 from South Beloit to Dixon. It then followed south on (roughly) present-day US 52, IL 251, and US 51.[5] In 1935, US 51 supplanted IL 2 south of Mendota.[6] With the appearance of US 52 in 1936, IL 2 was removed south of Dixon.[7] Then, in 1938, IL 2 was briefly extended to Muscatine, Iowa, replacing IL 84 and IL 86 in the process.[8] It soon got cut back to Rock Island in 1939 after IL 92 was extended to Muscatine.[9][10] By 1979, IL 2 was removed west of Sterling as Illinois Route 5 (now I-88 east of I-80) was extended to Rock Island.[11][12] To this day, exit 2 on I-88 is designated as "Old IL 2", referencing the pre-1979 routing of IL 2.[13]
^Illinois Secretary of State; H.M. Gousha (1928). Illinois Official Auto Road Map (Map). [c. 1:950,000 and c. 1:1,110,000]. Springfield: Illinois Secretary of State – via Illinois Digital Archives.
^Illinois Secretary of State; H.M. Gousha (1935). Official Road Map Illinois (Map). [c. 1:950,000 and c. 1:1,110,000]. Springfield: Illinois Secretary of State – via Illinois Digital Archives.
^Illinois Secretary of State; Rand McNally (1936). Road Map Illinois (Map). [c. 1:950,000 and c. 1:1,110,000]. Springfield: Illinois Secretary of State – via Illinois Digital Archives.
^Illinois Secretary of State; Rand McNally (1939). Illinois Road Map (Map) (1939–1940 ed.). c. 1:918,720. Springfield: Illinois Secretary of State – via Illinois Digital Archives.
^Illinois Department of Transportation (1977). Illinois Highway Map (Map). [1:772,500]. Springfield: Illinois Department of Transportation – via Illinois Digital Archives.
^Illinois Department of Transportation (1979). Illinois Highway Map (Map). [1:772,500]. Springfield: Illinois Department of Transportation – via Illinois Digital Archives.
