Situated within the Cordillera Central range in northern Luzon, it stretches from the city limit[2] of Baguio to the municipality of Bontoc.

[3] Its highest point is at 2,255.52 metres (7,400.0 ft) above sea level in the municipality of Atok.

It also covers four Mountain Province towns (Bauko, Sabangan, Bontoc, and Sagada).

Under Halsema's term, its construction commenced in 1922 with the help of locals and was completed in 1930 as a foot trail.

Parts of the highway are dangerous, especially during the rainy season, when landslides are common and asphalted portions become slippery.