[1] The highway begins in front of the Executive Yuan in downtown Taipei.

The highway passes through mountainous regions and enters Shiding and Pinglin in New Taipei City before reaching Yilan County.

The highway passes through Toucheng, Jiaoxi, Yilan City, Wujie, Luodong, and Dongshan before entering Su'ao.

The highway connects the townships of Ji'an, Shoufeng, Fenglin, Guangfu, Ruisui, Yuli, and Fuli in Hualien County, as well as Chishang, Guanshan, Luye, Yanping, and Beinan, before reaching Taitung City.

In August 2015, the 9A branch line of the highway passing through Wulai District, New Taipei City was cut by landslides due to Typhoon Soudelor.