The Buffalo Storm (Clarion, 2007) is a beautiful book.  Beautifully written by Katherine Applegate in her picture book debut; beautifully illustrated in watercolor and pastel by Jan Ormerod.  The kids (and I) have wanted to read it over and over again, for different reasons:  I'm moved by brave Hallie's having to leave her grandmother behind when she and her parents go west to Oregon on a wagon train; Leo likes the part in Wyoming where Hallie rescues a buffalo calf and then faces the buffalo storm; and Milly likes the end, Hallie at home in Oregon with a new baby sister wrapped in her grandmother's quilt.  I think that covers the whole story!  Reviewed by Tasha Saecker of Kids Lit here; I remembered her excellent review when I saw The Buffalo Storm on the new books cart at the library (although I think I would have checked it out anyway; Ormerod's illustrations are breathtaking).  And highly recommended by me, here.