Four hundred years. A vast geography. Making and Breaking Settler Space explores how settler spaces have developed and diversified from contact to the present. Adam Barker traces the trajectory of settler colonialism, drawing out details of its operation that are embedded not only in imperialism but also in contemporary contexts that include problematic activist practices by would-be settler allies. Unflinchingly engaging with the systemic weaknesses of this process, he proposes an innovative, unified spatial theory of settler colonization in Canada and the United States that offers a framework within which settlers can pursue decolonial actions in solidarity with Indigenous communities.