Illinois Route 47 is a largely rural north–south state highway that runs from the Wisconsin state border at Highway 120 near Hebron, to Illinois Route 10, just south of Interstate 72 near Seymour. This is a distance of 169.76 miles (273.20 km). Even though Route 47 is primarily rural, in several suburbs of Chicago, such as Woodstock, traffic can be congested. Even in heavily rural areas, traffic is heavy.

It crosses most Interstate highways in northern and central Illinois, but the largest towns that Illinois 47 serves are Huntley (at the Jane Addams Memorial Tollway), Yorkville (at U.S. Route 34), Woodstock (at U.S. Route 14), Lily Lake at (Illinois Route 64), Elburn (at Illinois Route 38), Sugar Grove (at U.S. Route 30), Morris (at Interstate 80), Dwight (at Interstate 55), Forrest (at U.S. Route 24), Gibson City (at Illinois Route 54), and Mahomet (at Interstate 74).

Illinois 47 overlaps Illinois Route 72 and U.S. Route 20 at Pingree Grove, a village approximately 60 miles (97 km) from Chicago; this concurrency is part of a so-called wrong-way concurrency, where one can be driving both west on Illinois 72 and east on U.S. 20 at the same time. Route 47 also shares concurrencies with Illinois Route 9 and Illinois 54 in Gibson City, U.S. Route 30 in Sugar Grove, U.S. Route 6 in Morris, Historic U.S. Route 66 in Dwight, and U.S. Route 150 in Mahomet.

The Prairie Parkway study is a preliminary study by the Illinois Department of Transportation for a limited-access freeway that will roughly parallel Illinois 47. According to the study's Final Environmental Impact Statement, Illinois Route 47 will interchange with Prairie Parkway approximately 1/2 mile south of Caton Farm Road near Yorkville.

The Illinois Department of Transportation is proposing to add lanes to several portions of Illinois Route 47. A project to reconstruct the road to 4 lanes from Kreutzer Road to Reed Road through Huntley was completed in October 2011. The Prairie Parkway study included engineering for 4 lanes from I-80 in Morris to Caton Farm Road south of Yorkville. Engineering is underway for Caton Farm Road to Illinois Route 71 in Yorkville, from Kennedy Road in Yorkville to US 30 in Sugar Grove, and from Charles Road to US 14 in Woodstock. A project providing additional lanes through Yorkville is part of the Illinois Jobs Now capital improvement plan and is funded at $36.5 million for construction.

In addition, proposals have been made to reconstruct both the I-90 and I-88 interchanges with Illinois Route 47 to full access. Currently, there is no westbound access or eastbound entrance at I-90 and no eastbound access or westbound entrance at I-88. Construction on the I-90 and Route 47 full interchange project has begun and will be completed in 2013, while the I-88 and Route 47 full interchange project is still in planning stages.

The Illinois Department of Transportation revealed in their 2010-2011 budget that they would no longer support the idea of the Prairie Parkway, mainly due to budgetary constraints, coupled with large public opposition. Instead, IDOT supported the idea of widening IL 47, since it runs directly from Interstate 88 to Interstate 80. Currently, the IL 47/I-80 interchange in Ottawa is a full interchange, while the interchange for IL 47/I-88 is split with a westbound entrance ramp and eastbound exit ramp directly connecting the two highways, while the westbound exit and eastbound entrance are accessible from I-80 via IL 56 and Galena Boulevard in Sugar Grove.