Plainsong for Caitlin — Elizabeth M. Rees

Caitlin
With the terrible news of a disaster at sea, fifteen-year-old Caitlin's world crumbles, as does that of her older sister Rebecca. Orphaned and with meager funds, the sisters leave New Bedford to begin a new life on the western frontier.

Sweetgrass, Nebraska-1872
It was Rebecca's decision to go west, yet it is Caitlin who blossoms with the beauty and strength of the prairie itself. Challenged by the relentless hard work and life-threatening struggles that overwhelm timid Rebecca, Caitlin is enchanted by the wild and rugged American west. And it is here that she discovers a love as dangerous and compelling as the land...and as forbidden as any passion she has ever known.