Cities worldwide are embracing innovative approaches with technology, management, and policy to target sustainable growth. These cities have seized “smart city” as a term around which they can coalesce and promote new sustainability initiatives although there is no academic or industry consensus around what the term means. Without a shared construct, these smart city initiatives are focused on sectoral improvements rather than defining the smart city as matter of cross-sector, or horizontal elements. This study identifies and validates a common smart city definition that describes the smart city and its characteristics based on an extensive content analysis of academic and government literature representing over 113 cities and corroborated through empirical case studies. This study also validates primary motivators which could indicate bias toward certain industries. Further, this study presents a maturity model, influenced by this study’s findings, with which cities can implement cross-sector smart city initiatives to achieve more interoperable outcomes.