Lateral channel migration initiates complex and dynamic biogeomorphic responses that are fundamental to the creation and maintenance of riparian habitats along low-gradient, coastal plain rivers. This study examines the effects of lateral migration rates on the structure and composition of riparian forests along the Congaree River, Congaree National Park, in the Atlantic Coastal Plain, South Carolina. Lateral channel migration rates were measured in a GIS using aerial photos from 1938–2006. Forest variables were measured from a stratified-random sample of 25 paired edge-interior plots, and analyzed using Mann-Whitney tests, Spearman's correlations, multi-response permutation procedures (MRPP), and non-metric multi-dimensional scaling (NMS) ordinations. Lateral channel migration produced a significant directional control on riparian forests. Pointbar forests exhibited classic forward succession dependent on spatial and temporal controls related to elevation, flood frequency, and lateral migration rates. Cutbank forests responded positively to exposure along the edge and increased in structural complexity with increasing proximity to the river; density, basal area, and richness varied inversely with lateral migration rates. Cutbank edges with low lateral migration allowed longer time for trees to colonize and they contained greater density, basal area, and richness. Cutbanks with high lateral migration contained lower tree density, basal area, and richness.