U.S. Route 20 (US 20) in Indiana is a main east–west highway that is parallel to the Indiana Toll Road. The western terminus of US 20 is at the Illinois state line and the eastern terminus is at the Ohio state line. US 20 through Whiting, East Chicago, and Gary is concurrent with US 12 twice. The route varies between one-way, two-lane, and four-lane streets, in Northwest Indiana. From the east side of Gary to west of South Bend, US 20 is a four-lane undivided highway. The route then heads around the west and south sides of South Bend and Elkhart as a four-lane limited access divided highway. East of State Road 15 (SR 15), US 20 is two-lane rural highway.
US 20 was part of the Dunes Highway from the Illinois state line to Michigan City, concurrent with US 12. The Dunes Highway started being paved in 1922. The section of the highway that is known as Lincoln Way was part of the 1913 section of the Lincoln Highway. Indiana State Highway Commission, later renamed Indiana Department of Transportation (INDOT), began signing US 20 in 1926. US 20 went through downtown South Bend and Elkhart before the St. Joseph Valley Parkway was built. Before the parkway was completed, the route that was open to traffic was called US 20 Bypass (US 20 Byp.). A small realignment in LaGrange County was done in 2005, in which the roadway was straightened. Other small realignments included the route through Michigan City, which followed US 35 from US 12 to Interstate 94 (I-94).
Route description
Only the segment of US 20 that is concurrent with the St. Joseph Valley Parkway is included as a part of the National Highway System (NHS). The NHS is a network of highways that are identified as being most important for the economy, mobility, and defense of the nation. The highway is maintained by INDOT like all other U.S. Highways in the state. The department tracks the traffic volumes along all state highways as a part of its maintenance responsibilities using a metric called annual average daily traffic (AADT). This measurement is a calculation of the traffic level along a segment of roadway for any average day of the year. In 2010, INDOT figured that lowest traffic levels were the 3,390 vehicles and 1,090 commercial vehicles used the highway daily near the Ohio state line. The peak traffic volumes were 36,040 vehicles and 731 commercial vehicles AADT along the section of US 20 concurrent with SR 331.
Illinois to South Bend
US 20 enters Indiana concurrent with US 12 and US 41, at which point it passes under the Indiana Toll Road. The road passes by both commercial and industrial areas, between Wolf Lake and Horseshoe Casino. US 12, US 20, and US 41 are concurrent until US 41 turns south on Calumet Avenue. US 12 and US 20 head southeast toward East Chicago; in East Chicago, US 12 turns east and US 20 continues south. US 20 meets SR 312 and passes under the Indiana Toll Road. US 20 turns left onto Michigan Street and heads east to Gary passing both industrial and residential areas. On the way to Gary, US 20 has an interchange with SR 912; at the interchange, the road name changes to 5th Avenue. Just west of Gary, US 12 and US 20 have a concurrency.
US 12 and US 20 are concurrent through most of Gary. From Bridge Street to Vermont Street, the eastbound traffic of US 12/US 20 is on 5th Avenue and westbound traffic is on 4th Avenue. East of Downtown Gary, the eastbound and westbound lanes merge to form the Dunes Highway. Before reaching the neighborhoods of northeastern Gary, the Dunes Highway has an interchange with I-65 and I-90/Indiana Toll Road.
Shortly thereafter, US 12 leaves to the northeast toward Michigan City and US 20 heads east then northeast, forming a major retail corridor through the neighborhoods of Aetna and Miller Beach. US 20 then meets SR 51 at the state road's northern terminus, near the boundary between Lake Station and Gary. Just west of Portage, the road passes under I-94. In Portage, the route has intersections with both SR 249 and SR 149. The road now enters Burns Harbor and has interchanges with I-94 and SR 49, just south of Indiana Dunes National Park. The route heads northeast until Town of Pines, where it intersects with SR 520. After Pines, the route heads due east to US 421 in Michigan City.