Drawing on recent theories of materiality and non-human agency, this article examines the aftermath of a compelling episode in American history, the Mountain Meadows massacre of 1857. In particular, I focus on certain ‘extensions’ of the massacre victims, as they encounter and become entangled with other material traces and embodied remembrances over the course of the twentieth century. An initial illustration of this process is drawn from the life history of an Arkansas native whose movements to and from his homeland have entangled him in the vast assemblage brought together by the events at Mountain Meadows. I then turn to the rupture in this assemblage that was triggered in 1999 by the exposure of human bones at the massacre site. Materiality theory highlights the ways in which some objects (or their parts) persist and remain inalienable, while others circulate with varying degrees of freedom. Patterns of persistence and circulation are analysed here by focusing on two kinds of objects with intimate ties to the massacre victims: the bodies of the 17 surviving children, and six buttons made of glass and metal.