There are some wonderful rumors relating to the origin of Congdon. From Cornwall in the UK came a band of Congdons who taking offense at their relatives joining the Normans to invade Eireland, stayed there and retained the spelling while the Irish branch became Condon. This might be true in that the Nova Scotia immigrants both Condon and Congdon separated themselves in the spelling. Even in one family the religion and family disputes presented a third spelling "Conden." There are some good people on this forum who have related various origins, royalty (Earl of Pembroke)in Wales, a Baron de Condetin in Eireland, after the Norman invasion and a group around the Blackwater River in Cork, Ireland who seem to be the descendants of the invasion previously said. I put my money on the Cornwall Congdons since they have the longevity but I won't know for sure 'till I get there and do some research for myself. Keep digging. A step backwards is great progress!