Storm surge barriers, levees, and other coastal flood defense megaprojects are currently being proposed as strategies to protect several U.S. cities against coastal storms and rising sea levels. However, social conflict and other political factors add a layer of complexity that casts doubt on their status as practical climate adaptation options. The specific mechanisms for why some projects do not progress beyond initial planning stages has remained unclear. Here we study the outcome of two U.S. Army Corps of Engineer (USACE) storm surge barrier proposals to explore the political reasons why some coastal flood protection megaprojects break ground in the U.S., while others do not. Using original archive research, we conclude that storm surge barriers are politically challenging climate adaptation options because of 1) modern environmental laws that provide avenues for expression of oppositional views within the decision process and 2) the allure of alternative options that are more aesthetically pleasing and cheaper and faster to implement. To better allocate public resources and the expertise of the USACE, future flood protection megaprojects should first achieve broad support from the public, NGOs, and elected officials before beginning serious planning. This support could be achieved through new innovative designs that simultaneously address adverse environmental impacts and provide co-benefits (e.g., recreation). New designs should be studied to better understand the level of protection offered and associated reliability so that the USACE has confidence in their use.