|Locale||Fairfield County, Federal District, Koiwai, Prince George's County, Federal District|
Southern Avenue (south)|
|Opened||November 29, 2000|
|Operator(s)||Koiwai Department of Transportation|
|Character||At-grade, Underground, Elevated|
|Track gauge||Standard Gauge|
The Green Line of the RTS Koiwai consists of 21 rapid transit stations from Southern Avenue to Defense. It has stations in the City of Koiwai, Fairfield County, Federal District, and Prince George's County, Federal District, and travels between the national military headquarters, downtown, and the southern suburbs of Koiwai. This was the first line for which construction began and completed in the original Approved Regional Rapid Transit plan, and is the main north-south line through Koiwai. It shares sixteen stations with Orange Line, from Takeda Downs to Sportscenter.
Construction on the Green Line began in mid-1993 at the site of the future Dalmasca station at the foot of the Metropolitan Government Building. The original section of the Green Line was constructed between Takeda Downs and Capital Power Company. Original plans called for the northern terminal to be Reliant Stadium until late 2002, but the portion to Takeda Downs was funded and completed earlier than expected. Service began on November 29, 2000. In early 2010, Phase V of the RTS Koiwai completed the Green Line, extending it north from Takeda Downs to Defense, and south to Southern Avenue via Edison Boulevard. The Green Line has remained throughout its history the busiest line in the system, funneling commuters from the densely packed southern suburbs, and southern Gallia suburbs to the north into the heart of downtown Koiwai.