Mountain peaks influence local climate, are proxies for topographic youth and exhumation, and are the most recognized features of mountain belts, yet are largely incidental to the modern conceptual framework of orogenic erosion that is focused on valley incision. Here it is shown that the three-dimensional distribution of prominent peaks is related to the confluences of major divides and thus to drainage basin structure. Divide-junction summits dominate mountain landscapes in both glacial and fluvial settings and likely result from the inherent stability of pyramidal peaks, in terms of both protection from valley erosion and greater mechanical stability relative to linear ridges. The potential stability of divide-junction peaks may make them anchor points for drainage divide networks, and thus the peaks work against the tendency of drainage divides to migrate. The influence of divide structure on peak heights also suggests that differences in headwall retreat rates may result in different frequency and relative relief of peaks in glacial versus fluvial settings. These results imply that interfluve topography and drainage divide structure offer relevant information for the understanding of landscape evolution.