Mary traveled with her family on the ship Zetland arriving in New Orleans on 26 December 1849. On the ship the surname was spelled "Giffen".
Mary's name was included both in the company report and on the immigration list published in Deseret News. Death records are listed under the married name of Mercer.
Birth date listed was found in a personal, online family history record (such as Family Tree, Ancestry, or My Heritage), without any accompanying documentation. Further research is needed to verify its accuracy.