Salt marshes are dynamic ecosystems that change in response to natural and human factors. This study used digitization of historical charts and imagery and the Analyzing Moving Boundaries Using R toolkit to measure approximately 70 years of change in lateral marsh extent and the distribution of interior features (ponds, upland, channels, and flats), in marshes of the Georgia Coastal Ecosystems (GCE), Virginia Coast Reserve (VCR), and Plum Island Ecosystems (PIE) LTER sites. Measuring the marsh edge exposed to high fetch and along channels was important for providing complete information on marsh change. GCE was dynamic, but total marsh area was conserved. VCR experienced marsh loss to flat expansion, which was offset by marsh migration, and overall marsh area was conserved. PIE was erosional, losing marsh along the outer edge, channel widening, and ponding. GCE was considered the most resilient, because of its tidal range, sediment supply, and elevation.