Italian vital records and church records were kept at the town level, so you have to know the town in order to find the records. There may be US records that list the town. If you are willing to give us their names, approximate birth years, and where they lived in the US, we might be able to help you find more information.
Dear Ms. Blaustein,
Thank you for posting your request on History Hub!
Since some U.S. census records will indicate the year that the person immigrated and/or was naturalized, we suggest reviewing the NARA’s Online Census and Other Resources using the link to the National Archives Catalog. All the U.S. census population schedules are part of the Records of the Bureau of the Census (Record Group 29). Beginning with the 1850 census, each person listed. The information generally includes the person's name, relationship to head of the household, sex, age, marital status, occupation, place of birth, citizenship, and education. Some of these schedules are digitized. To obtain a copy or view the non-digitized records, please contact the National Archives at Washington, DC - Textual Reference (RDT1) via email at firstname.lastname@example.org.
Due to the COVID-19 pandemic and pursuant to guidance received from the Office of Management and Budget (OMB), NARA has adjusted its normal operations to balance the need of completing its mission-critical work while also adhering to the recommended social distancing for the safety of NARA staff. As a result of this re-prioritization of activities, you may experience a delay in receiving an initial acknowledgement as well as a substantive response to your reference request from RDT1. We apologize for this inconvenience and appreciate your understanding and patience.
Ancestry has digitized the U.S. census population schedules and they are searchable by name. In response to the COVID-19 pandemic, the National Archives has partnered with Ancestry to make the vast majority of their NARA-digitized holdings freely available to the public. Anyone with Internet access may create an account, access NARA records, and use other Ancestry resources, such as their educational offerings and family tree-maker application. For more information see Ancestry’s announcement -- “Free At-Home Education Resources From Ancestry® and Access to Nearly 500M National Archives Records.”
You may wish to search Ancestry or FamilySearch for the U.S. Census. There may be a fee for using Ancestry. Instead, please check for access at your local library as many library systems subscribe to these sites, making them free for their patrons.
Under Italian law, records of births, marriages, and deaths are maintained by the Registrar of Vital Statistics (Ufficio dello Stato Civile) in the city (comune or municipio) where the event occurred. There is no central, regional, or provincial office established which keeps such records. Please review the FamilySearch Research wiki for Italy Civil Registration and the U.S. Embassy in Italy webpage on Obtaining Vital Records for more information.
We hope this is helpful. Best of luck with your research!