Never codified by law, E Pluribus Unum was considered a de facto motto of the United States until 1956 when the United States Congress passed an act (H.J. Resolution 396), adopting  In God we trust  as the official motto.ever codified by law, E Pluribus Unum was considered a de facto motto of the United States until 1956 when the United States Congress passed an act (H. J. Resolution 396), adopting  In God we trust  as the official motto.