Geographic demarcations

• Green Line (Cyprus), a cease fire line between the Republic of South Cyprus and the Turkish Republic of Northern Cyprus
• Green Line, a name for the Gothic Line of "Linea Gotica", a German defensive line in Italy during World War II, renamed the "Green Line" in June 1944
• Green Line, the disputed border between India and Pakistan in the Sir Creek area
• Green Line (Israel), the 1949 Armistice lines established between Israel and its neighbours: Syria, Jordan, and Egypt
• Green Line (Lebanon), a line of demarcation in Lebanon between Christian and Muslim militias in Beirut during the Lebanese Civil War
• "Green Line", an urban growth boundary for Virginia Beach, Virginia

Public transit

Public transit companies

• Green Bus Lines, a private New York City bus company now part of the public MTA Bus Company
• Green Line Coaches, a commuter coach company, part of the Arriva group, operating services from London, England
• New York Railways, a former street railway, also known as "Green Lines"

Public transit in Asia

• Chūō Line (Osaka), Japan
• Dzerzhinskaya Line, Novosibirsk, Russia
• East West MRT Line, a rapid transit line in Singapore
• Green Line (Dubai Metro), United Arab Emirates
• Green Line (Taipei), Taipei Rapid Transit System, Taipei, Taiwan
• Green Line (Yokohama), a subway line in Yokohama, Japan
• Kwun Tong Line of Hong Kong MTR, Hong Kong, China
• Seoul Subway Line 2 (South Korea)
• Shanghai Metro Line 2 (PR China)
• Tokyo Metro Chiyoda Line, a line in Tokyo, Japan

Public transit in the United States

• Blue and Green Lines (Cleveland), a light rail line
• D Line (RTD), Denver, Colorado
• Fremont–Daly City line, a rapid transit line in the San Francisco Bay Area's BART system
• Green Line (Baltimore), a proposed transit line
• Green Line (Boston), a light rail network which includes the oldest subway tunnel in the U.S.
• Green Line (Chicago), a rapid transit line
• Green Line (Dallas), a future light rail line
• Green Line in the Seattle Monorail Project, the planned first line in a now-defunct plan to build a monorail system
• Green Line (Washington Metro), a rapid transit line
• IRT Lexington Avenue Line in New York City
• MAX Green Line, light rail route currently under construction in Portland, Oregon
• Metro Green Line (LACMTA), a light rail line in the Los Angeles Metro Rail system
• Miami-Dade Metrorail, a rapid transit line in Florida
• Green Line, a light rail line in the San Diego Trolley system
• SEPTA Subway–Surface Trolley Lines, a light rail network in the Philadelphia area

Public transit in Canada

• Bloor-Danforth (TTC) line, a rapid transit line of the Toronto Subway
• Evergreen Line (Vancouver), a proposed line in Vancouver, British Columbia
• Line 1 Green (Montreal Metro), a rapid transit line in Montreal
• Viva Green, a rapid bus transit line in and around Toronto

Public transit in Europe

• Alekseevskaya Line, Kharkov, Ukraine
• Barcelona Metro line 3, Barcelona, Spain
• District line, on the Underground in London, England
• Green Line on the Luas, one of the two tram lines in Dublin, Ireland
• Green Line, one of the two lines in the Tyne and Wear Metro, North East England
• M1 (Copenhagen), Denmark
• Line 5 (Madrid Metro) in Madrid, Spain
• Line A (Prague Metro)
• Line M2 - Milan Subway (Metropolitana di Milano), a rapid transit line in Milan, Italy
• Lyon Metro Line D in Lyon, France
• Nevsko-Vasileostrovskaya Line in the Saint Petersburg Metro (Russia)
• RER D, Paris, France
• Green line of the Stockholm Metro
• Syretsko-Pecherska Line, Kiev, Ukraine
• Zamoskvoretskaya Line, Moscow, Russia

Other uses

• Green Line (magazine), a UK magazine