Born in Gunzenhausen, Bavaria, in 1820, Meier Rosenbach was one of Philip Heymann Rosenbach and Adelheid Rosenbach’s four children. He immigrated to the United States in 1844, settling in Philadelphia, changing his name from Meier to Morris. He went into the clothing business, selling overalls and underwear. He became a citizen of the United States in 1855, and two years later married Isabella Polock, in a wedding officiated by Isaac Leeser. The couple had eight children, including Philip. The family was involved in Jewish life in Philadelphia and were mebers of Congregation Mikveh Israel.