Trial runs on Line 1, a 23 km north-south route, started in March 1999. After six years of construction it opened for regular service on 6 October 1999 as the fourth subway system in South Korea after Seoul, Busan and Daegu. A trip along the line from Gyeyang in the north to Dongmak in the south takes approximately 45 minutes. Bupyeong station is a transfer point to Korail, a route which is actually integrated into Seoul's subway network as an extension of Seoul's Line 1. Incheon's subway is totally underground except north of Bakcheon.
A one-station extension to Gyeyang, for connections with AREX, opened in March 2007. A six-station south extension opened in June 2009.