The Hangang is approximately 497km-long with its basin measuring at 26,219 square kilometers. Its watercourses cover extensive regions of the middle part of country, including Gangwon-do, Chungcheongbuk-do, and Gyeonggi-do provinces.
 

According to the Korean National Geographical Association, the fountainhead of the Hangang is located on the northern valley on Geumdaesan(Mt.) in Gangwon-do. Tributaries of the river include 62 streams, which are under the direct control of the central government, 55 regional streams managed by each local government, and 3,847 others. The total length of the tributaries reaches 7,430km.

Since the ancient Three Kingdoms Era on the Korean peninsula , the Hangang has been holding a geopolitical importance. Since Taejo, Yi Seong-gye, the founder of the Joseon Dynasty (1392-1910), designated Hanyang (today's Seoul), through which the Hangang ran, as the nation's capital 600 years ago, Seoul has been playing political, economic, and cultural centers of Korea.