Due to the removal of almost every numbered route in Indianapolis, US 136 never meets its parent, US 36; however, it does come within two miles of it at its interchange with I-465/I-74 at its eastern terminus.

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.

US 136 in Iowa consists of a 3.6-mile-long (5.8 km) route which travels across the south-easternmost tip of Lee County.

At the intersection with Main Street, which is the southern end of US 218, it turns to the southeast towards the Mississippi River.

US 136 travels another 2⁄3 mile (1.1 km) before crossing the Mississippi into Hamilton, Illinois via the Keokuk–Hamilton Bridge.

It passes through historic Carthage; site of the death of Joseph Smith, founder of the Latter Day Saint movement and home of the Kibbe biological museum, then Macomb, 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.

This highway began at St. Joseph and followed present US 169 to Stanberry, turning east there to the Iowa state line along US 136.