Young Adult Literature; Historical Fiction; War Drama
The historical fiction part is fairly self-explanatory: The River Between Us is fiction, and it's set in the past—during the Civil War, to be precise—so it's historical fiction.
YA novels deal with young adults, i.e., teenagers or adolescents, who wrestle with identity and the world around them in some way. We have teens in both eras featured in this book grappling with who they are, where they come from, and who they want to be. In fact, just try not to read about teens while reading this book—it's pretty hard since the adults are all minor players.
And as for war drama, the Civil War is at the heart of this book. It haunts the pages, dragging Noah from home, taking his arm, and creating a very high-stakes setting for Delphine and Calinda, as well as everyone else. If that doesn't make this a war drama, then our name's not Shmoop.