"New York State Census, 1865," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:QVNJ-DLPB : 8 March 2021), Wm Mcmahon in household of Mcmahon, Ward 01, Oswego, Oswego, New York, United States; citing Census, p. 5, citing multiple county Clerks; Warren and Lewis County Board of Supervisors; multiple counties in New York; Utica and East Hampton Public Libraries, New York.
"Illinois, Cook County Deaths, 1871-1998," database, FamilySearch (https://familysearch.org/ark:/61903/1:1:Q2MK-WH28 : 18 March 2018), William McMahon, 13 Mar 1939; citing Chicago, Cook, Illinois, United States, source reference , record number , Cook County Courthouse, Chicago; FHL microfilm .
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