National Freeway 3, also known as Formosa Freeway, is a freeway in Taiwan. It is the second north–south freeway in Taiwan, beginning in Keelung City at Jijin Interchange on the provincial highway 2 and ending in Linbian, Pingtung on the provincial highway 17. It is the longest freeway in Taiwan with a total length of 431.5 km (268.1 mi). The freeway is also the only one in Taiwan to have a spur route, Freeway 3A.

Taoyuan is a special municipality located in northwestern Taiwan, neighboring New Taipei City to the north-east, Yilan County to the south-east, and Hsinchu County to the south-west. Taoyuan District is the seat of the municipal government and which, along with Zhongli District, forms a large metropolitan area. Taoyuan developed from a satellite city of Taipei metropolitan area to become the fourth-largest metropolitan area, and fifth-largest populated city in Taiwan. "Taoyuan" literally means "peach garden" in Chinese, since the area used to have many peach trees. Formerly a county, Taoyuan became the latest new founding special municipality in 2014.