The highway follows the Klickitat River and an abandoned railroad grade that was built in 1903 and converted into a recreational trail in the 1990s.

The two-lane, high-speed road is also paralleled to the west by the Klickitat Trail, a multi-use path for bicycles and pedestrians that uses an abandoned railroad grade.

[2] SR 142 continues to traverse several canyons, making several bends to the east and north to follow the course of the Klickitat River.

The highway crosses over the river near Wheeler Canyon and continues along its west bank to the town of Klickitat, where it serves as the main street.

The entire highway is also designated as a state scenic byway due to its proximity to recreational hunting, fishing, and watersports.

[6] The railroad was completed in April 1903, on a route following the Klickitat River Canyon to Wahkiacus and Swale Creek before reaching the southern outskirts of Goldendale.

[10] The timber truss bridges, located northeast of Wahkiacus, were replaced in 1955 by a pair of prestressed concrete spans that demonstrated an early use of the new technology.