Assuming that "Christmas 1910" refers to a literary or historical work, it is possible that the isolation of the farm in South Dakota creates a sense of loneliness or detachment for Abigail. This could be ironic in that Christmas is traditionally a time for gathering with loved ones and celebrating together, yet Abigail is separated from others on the farm.
Additionally, the isolation of the farm could be seen as a symbol for the isolation and hardships that early settlers faced in the American West. This could add to the irony, as Christmas is typically associated with comfort, joy, and abundance, but for Abigail and her family, it represents a time of struggle and survival.