I've traced back my Cambridge name to Maryland,USA, c. 1730. Before that, not sure. In addition to Cambridge, Cambridgeshire, there is a much smaller town in, I believe, Gloucestershire,UK, called Cambridge. This may be the origin of the many Cambridges listed today in Bristol, which is the closest large city. Also, perhaps, some of the Cambridges from Ireland, of whom there are many. Or these may be descendants of Cromwell's troops from East Anglia who settled in Ireland. Cambridge is a relatively rare name, but seems to have several possible origins. It is also a surname for many black families in the West Indies.
I will try to check your tree on ancestry.com to see if there are any clues there. Thanks for your message.