William "Elmo" Mercer, Sr. ("Mo" to his friends) was born to William Fred Mercer and Lottie Johnson Mercer in Pollock, Louisiana, on February 15, 1932, and passed away at his residence in Leander, Texas, at the age of 88 years old. W. "Elmo" Mercer lived and worked in Nashville for many years in the music industry.
Mo was a lover of music; singing, writing, playing; he loved it all. He began taking piano lessons as a child and was 14 years old when he wrote his first song which was titled “A Glimpse of Jesus.” Before the age of 20, he wrote what is possibly his most popular song, “Each Step I Take." In 1998, his song “What A Glad Reunion Day” was included in the soundtrack of the “The Thin Red Line” a 20th Century Fox movie.

Mercer completed two 30-year careers. He worked full-time for the John T. Benson company from 1951 to 1981 initially as a staff writer and later rising the the position of Music Editor. During his time at Benson, the company published the popular New Songs Of Inspiration series of hymnbooks which Mercer edited. He also published numerous instrumental books and choral works including the popular Crusade Choir, Vol. 1 and edited the 1979 National Baptist Hymnal. At his passing had written over 1600 songs.