The dynamic convergent systems along the western margin of the Americas offer exceptional natural laboratories for studying subduction and related plate-boundary processes across a broad range of spatial and temporal scales. Long-lived convergence has generated complex records of mountain building, basin and landscape evolution, magmatism, and margin reorganization. Today, these boundaries remain actively deforming, producing seismicity, volcanism, and vertical motions that pose significant hazards to densely populated regions. This session welcomes contributions on short- and long-term plate-boundary processes, including active deformation, seismicity, magmatism, fluid circulation, deformation partitioning, mantle dynamics, landscape evolution, and plate-kinematic changes. We particularly encourage studies that integrate present-day observations with the geological and tectonic record—such as investigations of arc initiation and extinction, flat-slab subduction, terrane accretion, subduction of seismic and aseismic ridges, slab breakoff, slab-window development, vertical motions, and surface-process interactions. We also welcome multidisciplinary approaches drawing on geophysics, seismology, geodesy, structural geology, geomorphology, geochronology, geochemistry, and numerical or analogue modeling. By bridging regional and process-based perspectives, this session aims to foster dialogue among communities working on active tectonics, geological reconstructions, landscape evolution, and geodynamic processes, and to advance our understanding of how convergent margins initiate, evolve, reorganize, and terminate over geological time.