Depopulation: infrastructure challenges and opportunities

Abstract Depopulation is projected to occur in half of US cities by 2100 and represents a potentially destabilizing dynamic for infrastructure. Maintaining and managing infrastructure systems that were built for a growing population will become a challenge with depopulation. Reduced tax bases in depopulating cities will translate to financial challenges, including reduced funding streams for infrastructure maintenance, rehabilitation, and modernization. At the same time, infrastructure systems in many cities will be extended past their initial design lives. These compounding challenges call for a fundamental rethinking of infrastructure planning, design, construction, and maintenance practices. Strategies to confront depopulation include a shift toward modular and multifunctional systems to enhance infrastructure flexibility and efficiency. Additionally, adaptive reuse, smart infrastructure, and coordinated downsizing can help allocate resources efficiently while maintaining functionality. From materials science and civil engineering to computer science and public policy, addressing these challenges requires major scientific advances that may open up new research opportunities.