Er ist verheiratet mit Mary E. Ketcham.
Sie haben geheiratet im Jahr 1869 in Toledo, Lucas County, Ohio, er war 43 Jahre alt.
Portrait and biographical record of city of Toledo and Lucas and Wood Counties, Ohio : containing biographical sketches of prominent and representative citizens of the locality : together with biographies and portraits of all the presidents of the United States. Chicago: Chapman Pub. Co., 1895 page 386.
"Mars Nearing was born 22 Jun 1825 in LeRoy, NY, the son of Neptune Nearing and Eunice Bonney. His only sibling, sister Eunice Nearing, died in New York in 1892. He married Mary E. Ketcham in 1869, and no children are listed; no date of death. His father, Neptune Nearing, was born in Vermont, and after his marriage, moved to NY state. Neptune Nearing died in 1846".