"United States Census, 1900," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:M317-64L : accessed 26 April 2020), Carl Henry Rohwer in household of George Rohwer, Calhoun Township Calhoun city, Washington, Nebraska, United States; citing enumeration district (ED) 127, sheet 11B, family 210, NARA microfilm publication T623 (Washington, D.C.: National Archives and Records Administration, 1972.); FHL microfilm 1,240,941.
"United States Census, 1920," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:MXLM-ZP7 : accessed 8 May 2020), Carl Rohwer in household of Mary J Nelson, Fort Collins Ward 5, Larimer, Colorado, United States; citing ED 157, sheet 10B, line 97, family 27, NARA microfilm publication T625 (Washington D.C.: National Archives and Records Administration, 1992), roll 166; FHL microfilm 1,820,166.