<p>Adaptation to climate change often involves making sequential decisions in pathways to adjust to the deep uncertainty of the future climate as it unfolds. These paths, whether chosen intentionally or not, can result in positive or negative outcomes as the dynamics of the system unfold and as environmental and social conditions change over time; the initial actions may severely limit robust options in the future. Historical pathways analysis can be combined with Dynamic Adaptive Policy Pathways (DAPP), a sequential, adaptation pathways planning approach, to illustrate the global significance of considering the impacts of pathway selection in urban development and adaptation by analyzing the recent and rapid development of Boston’s Seaport District, a flood-vulnerable neighborhood. It is demonstrated that the explicit disregard of pathways analysis led to heightened vulnerability to flooding, versus potential alternative pathways that include sequential and adaptive adaptation actions under uncertain sea level rise that generate lower costs and more environmental and social co-benefits. This novel application of adaptive pathways planning to a historical case study illustrates the importance of considering a broader adaptation space in planning, and the impacts, benefits, and long-term consequences of various adaptation options. Globally, such an approach to planning is of vital importance given the prevalence of ongoing flood-vulnerable development and the staggering costs of adaptation.</p>