How many light rail/subway systems go to the airport?

i want to know if anybody knows. i know portland,or has a light rail that goes to the airport. the subway in chicago goes to ohara and st louis has a light rail that goes to the airport plus new york city has one too

goto www.maps.google.com

enter your desired location, enter home and destintaion and you will get route which you can customize to show railways/subways