The surface geology of eastern North America is extraordinary in its complexity. This complexity reflects a wide range of tectonic processes that have operated in the region over the past billion years, including episodes of subduction and rifting associated with two complete Wilson cycles of supercontinent assembly and breakup. It is poorly known, however, how the deep crust and mantle lithosphere have responded to these tectonic forces over time; furthermore, the persistence of Appalachian topography through time remains a major outstanding problem in the study of landscape evolution. The deployment of the EarthScope USArray in eastern North America has opened up new frontiers in the study of the deep structure and dynamics of the crust, mantle lithosphere, and asthenospheric mantle beneath this passive continental margin. In this talk I will discuss recent results from the EarthScope project on the structure of the crust and upper mantle beneath eastern North America, with a focus on the central Appalachians and on New England.