U.S. Highway 136 is a spur of U.S. Highway 36. It runs from Edison, Nebraska, at U.S. Highway 6 and U.S. Highway 34 to the Interstate 74/Interstate 465 interchange in Speedway, Indiana. This is a distance of 804 miles (1,294 km).

U.S. 136 passes through the following states:

U.S. 136 closely parallels Nebraska's southern border from its western terminus near Edison to the Missouri River. It passes through Beatrice and exits the state at Brownville via the Brownville Bridge. It is designated the Heritage Highway throughout Nebraska.

US 136 enters Missouri on the west just east of Brownville, Nebraska, over the Missouri River. It leaves the state at Alexandria, Missouri, on the east concurrent with US 61. During its journey it enters every county seat in the nine counties it traverses. The distance across Missouri is around 240 miles (390 km). US 136 is two lanes for the full distance.

U.S. Route 136 in Iowa consists of a 3.6-mile (5.8 km) long route which runs across the south-easternmost tip of Lee County. It crosses the Des Moines River from Missouri with U.S. Route 61, overlapping for just over one mile (1.6 km). East of the US 61 split, US 136 is overlapped by US 61 Bus. through Keokuk. US 136 enters Keokuk along 7th Street, which takes a turn to the northeast towards downtown. At the intersection with Main Street, which is the southern end of U.S. Route 218, it turns to the southeast towards the Mississippi River. US 136 travels another 2⁄3 miles (1.1 km) before crossing the Mississippi into Hamilton, Illinois via the Keokuk–Hamilton Bridge.

U.S. 136 spends 225.95 miles (363.63 km) within the state of Illinois. U.S. Route 136 crosses the Mississippi River into Illinois from Iowa just past Keokuk. It passes through Macomb, Illinois, where Western Illinois University is located. It continues as an east–west route intersecting with I-155 and I-55 south of Bloomington-Normal and north of Lincoln in Central Illinois. It later intersects with I-74, and then I-57 just outside Rantoul about 15 miles (24 km) north of Champaign-Urbana. U.S. Route 136 then runs concurrent with Illinois Route 1 in far east central Illinois before entering Danville, Illinois. At Danville, it turns east to go into Indiana.

Through most of its duration in Indiana, 136 parallels Interstate 74. Within Indianapolis, the route is also called Crawfordsville Road, and US 136 ends in the town of Speedway, Indiana, at the I-465/I-74 interchange where Crawfordsville Road continues without numbered designation. As part of Indiana's Accelerate 465 project, the I-465/I-74 interchange is being reworked to eliminate tight spiral ramps and to add a full interchange for US 136 with I-465.

In Missouri, most of US 136 was designated as Route 4 in 1922. This highway began at St. Joseph and followed present US 169 to Stanberry, turning east there to the Iowa border along US 136. The rest of US 136 was initially Route 1A (Nebraska to Rock Port), part of Route 1, and Route 18 (Tarkio to Stanberry). The east end was truncated to Wayland in 1926, when US 61 was designated over the part east to Iowa, and later that decade Route 4 absorbed the former Route 52 from St. Joseph southwest to Atchison, Kansas. When this extension became part of US 59 in the early 1930s, the portion west of Stanberry was deleted in favor of US 59 and US 169; Route 4 was instead extended west, absorbing Routes 18 and 102 (the latter a ca. 1930 renumbering of Route 1A). US 136 replaced Route 4 east of Stanberry in 1951 and the rest in 1960.

In Nebraska, US 136 was previously "Route 3." US 136 replaced Route 3 in 1960.