In May 1895, the area containing present-day Gunpo became known as Nam-myeon, a division of Gwacheon-gun, but on 1 March 1914, a revision deemed that Nam-myeon now fell within Siheung-gun. Throughout the remainder of Japan's annexation of Korea and the first several decades of the Republic of Korea, no changes were made to the designation of Nam-myeon or to its administrative districts, but a presidential decree had the area promoted on 1 May 1979, to Gunpo-eup (town), which yet remained within Siheung-gun.