Where do the census records say the person is born?
-- Wherever the respondent reported the person was born. The accuracy of said responses is highly questionable. I have a ggf who was listed in consecutive census as having been born in Ireland, at sea, in PA. ============================ Would there be any birth records?
-- More than likely not. In some instances you might find a notation on a ship's manifest. There is a very slim outside chance that a delayed birth certificate was filed in some jurisdiction, but it probably will state a birth in that jurisdiction rather than at sea. Your most likely avenue would be a religious document, e.g. a baptismal certificate. ============================ What actual infomation do you seek from the census records or the birth record?