The Burnham family was converted to the Church of Jesus Christ of Latter-day Saints in May of 1843, which they soon moved from Bureau County, Illinois to Nauvoo, Illinois to be closer to the Church. While there, James was ordained a member of the Quorum of the Seventy of the Church while on his mission in 1844.

On Oct 8, 1845, James Lewis Burnham Jr. died.

Travel west was not easy for the Burnham family, as Mary had to spend all her time caring for her children, and hardly spent available time to make the means to go west. After being forced to go to Winters Quarters from mob attacks in Nauvoo, she lived in the camp for about a year and a half, before the US Government forced them out because they were on Native American land. Because Mary was unable to go out west, she had to let her sons Wallace and George go west without her.

The Burnham family moved to Bountiful, Utah where Mary made hats and knitted for finances. The Burnham family moved to Hyde Park, Utah were Mary Ann lived for about nine years before moving to Richmond with her sons.