Re: How to learn if an immigrant received US citizenship? #usa
Someone who immigrated to the US in 1958 (assuming they were admitted on an immigrant visa) would be eligible to naturalize 5 years later (sooner if they were married to a US citizen). As long as they applied (filed their Petition for Naturalization) prior to 1990/1992 that petition would be filed in a court with jurisdiction over their residence.* This research for this time period is fairly straightforward.
First, you can start looking for the court record. By 1960 most naturalizations took place in Federal courts. Many Federal court records are at least indexed online (Ancestry.com, FamilySearch, etc.), though not all of them for the late 20th century. If not online, the records should be at the National Archives. If the immigrant lived in a rural area they still might have naturalized in a state or local court. In that case one should look to that locality for naturalization research guidance.
Second, there is always the backup of a USCIS A-file. Any immigrant who arrived 1958 has an A-file which holds all their records, including the immigration visa records and copies of all the court naturalization records.
*If they were a member of the US military when they naturalized their records might be in a court with no relation to their residence. Also, if anyone applied for naturalization after 1990/92 all records are in the USCIS A-file.