According to Trafford R. Cole, in his book Italian Genealogical Records: How to Use Italian Civil, Ecclesiastical, & Other Records in Family History Research, the passport of an ancestor is typically found among the personal documents in the land of destination. It provides:
Later passports contain a photograph of the passport holder.
Obtaining information about a passport from Italy is another matter and often quite difficult. Since one of the first reasons for issuing passports was to regulate the travels of young men of draft age, the passports were the responsibility of the police and were issued by the questura in each province. The archives of the questuras are not open for public consultation. A request can be made to the prefettura (district attorney’s office), however, Mr. Cole reports in his book that he has not had any success obtaining passport information from this source predating the beginning of the 20th century.
Since all requests for passports had to be approved by the ministero degli interni (minister of internal affairs) in Rome, another source is the registri delle vivmazioni dei passaporti. It is necessary to know the passport holder’s comune of origin and the year the passport was released. The record gives the name of the passport holder, birth date, town of residence. and date of application. In some case the port of emigration departure and the destination are also indicated.
Mr. Cole’s book contains more complete information and is a must have for any serious researcher of Italian genealogical records