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The longevity of cratons usually implies that the entire cratonic lithosphere remained unchanged over billions of years, which is traditionally attributed to their intrinsically buoyant and strong lithospheric roots. By reviewing relevant studies and recent observational constraints, we show that the present cratonic roots are notably denser than the ambient mantle, with the compositional buoyancy offsetting only one-fifth of the negative thermal buoyancy. In addition, the presence of a weak mid-lithospheric discontinuity could decouple the upper and lower lithosphere upon perturbation, allowing delamination of the lower portion, while most of the delaminated lithosphere would eventually relaminate to the base of the lithosphere after sufficient warming inside the convective mantle. This process generates enduring (>100 Myr) and prominent (>1 km) surface uplifts within continents, a mechanism more compatible with data, especially those reflecting lithospheric deformation, than the model of all continents climbing up a steady region of dynamic uplift. Subsequent lithospheric cooling gradually draws the surface down to below sea level, where the lithospheric mantle density reaches a maximum upon formation of the next supercontinent. We argue that such cratonic deformation has happened repeatedly over supercontinent cycles since the Neoproterozoic and has largely shaped the properties of the present cratonic lithosphere. A few new research directions are also suggested. 

Abstract The crustal stress field determines continental deformation, including intraplate seismicity and topographic undulations. However, the sources of observed crustal stress patterns remain debated, with proposed mechanisms including lateral variations in gravitational potential energy and mantle flow, the latter of which comprises plate boundary interactions and basal tractions. Here, we present a series of geodynamic models that simultaneously consider lithospheric and mantle dynamics in the same physical framework, based on which we investigate the sources of crustal stress over the conterminous U.S. The data‐oriented nature of these models allows us to systematically explore the relative contributions of different dynamic sources to the three‐dimensional crustal stress field. These models reveal that forces from the plate boundaries play a dominant role in generating the directional pattern of long‐wavelength horizontal crustal stress across the conterminous U.S. In the central U.S., especially regions of high‐topography, lithospheric density heterogeneities locally modify the crustal stress field. Similarly, mantle flow beneath the North American plate modulates crustal stress orientation in the eastern U.S., particularly in regions with thin lithosphere. Furthermore, we find that a denser‐than‐ambient lithospheric mantle beneath the central and eastern U.S. is required to match the observed continental‐scale E‐W topographic contrast.