The Strengthening American Infrastructure (SAI) program aims to stimulate human-centered, use-inspired, fundamental, and potentially transformative research to strengthen America's infrastructure. This program focuses on integrating expertise from across all science and engineering disciplines to build and maintain effective infrastructure that improves lives and society. Successful projects will represent a convergence of expertise in one or more social, behavioral, or economic sciences, deeply integrated with other disciplines to support substantial and potentially pathbreaking fundamental research applied to strengthening a specific focal infrastructure. Key aspects of this opportunity include: * Proposals may be submitted by for-profit organizations, non-profit, non-academic organizations, institutions of higher education, and tribal nations. * PIs must hold appointments at U.S.-based campuses/offices of eligible organizations. * The estimated funding for this opportunity is $9,600,000, with an award ceiling of $750,000 and an award floor of $50,000.