Edith,I must apologize for not being able to get to my information - it is in another location.I have a "book," researched by a Mrs. Oatis(?) of Ohio, that fairly well outlines many of the branches and families.My Mom, during the 1970's, became interested in the history and found this individual as she had my Dad and Uncles listed.
In my opinion, Readfield is your key.There is a graveyard, located at the access to the Old Plains Road in Readfield, where many of Gordens / Gordons are buried.
I also found that the Town's Records show the birth of many of these individuals being listed with the spelling of Gordon, which many of them never used (i.e. Gorden).