Elam M. Day was born on March 22, 1849 in Ohio to Benjamin and Emeline Day. His father was a physician and clergyman who owned $350 of real estate in 1850. The family was living in Liberty, Ohio, in 1850, and they moved to Harrison, Ohio, sometime before 1870.
He enlisted in the Union army as a substitute on October 3, 1864, and he mustered into Company A of the 38th Indiana Infantry. In January 1865, he confessed that "I wish that I had volunteered instead of coming as a Substitute for the substitutes are reckoned with the drafted men and no honor will be confered on them unless they are noted for bravery or do some very valuable act for the gov[ernmen]t and I am not very brave nor either am I likely [to] do any valuable service although I will do my best for my country." He mustered out on July 12, 1865, and returned to his parents’ household in Harrison.
He attended school there before beginning work as a teacher. He married Mary E. Bright on July 31, 1872, and they had at least three children: Effie, born around 1875; Orson, born around 1877; and Charles, born around 1879. By 1880, they were living in Pyrmont, Ohio. His wife died sometime in the 1880s, and he married Barbara Farrar around 1887. They had at least two children: Leoti, born around 1889; and Catherine, born around 1894. By 1900, they were living in McArthur, Ohio, and Day was working as a newspaper editor. They moved to Huntsville, Ohio, in the 1910s, and he died there on December 13, 1928.