Agnes's sister, Sarah McGavin (Family Search ID: KWJD-RZK), wrote a letter to her father stating that her family – consisting of her mother, Janet, and her siblings, Agnes, James, Jeanette, Mary, and Robert – began their trek to Salt Lake City the week before her marriage, which was on April 20, 1859. More research needs to be conducted to determine which company they traveled in.
Agnes's record in the 1900 US census that her family immigrated to the United States in 1855. Unverified research had suggested that the family may have traveled to Utah in the Hooper and Williams Freight Train in 1855, but Sarah’s letter confirming the date of their departure suggests otherwise.
She married Robert McKendrick soon after his arrival in Salt Lake because she was rebaptized in Salt Lake City on 9 Oct. 1859 under the name Agness C. McKendrick according to information in the Eleventh Ward record of members. Robert McKendrick was rebaptized on the same date. She is enumerated in the 1860 census with Robert and his family.