It borders Pyŏktong and Chagang's Usi county to the north, Unsan and Songwŏn (in Chagang province) to the east, Thaechŏn to the south, and Changsŏng and Taegwan to the west.
Tongchang County is a kun, or county, in the northeast of the far western North Pyŏngan province, North Korea.