Trauma systems provide an organized approach to the care of injured patients within a defined geographic region. When fully operational, the systems ensure a continuum of care involving public access through 911 calls, emergency medical services, timely triage and transport to acute care, and transfer to rehabilitation services. Substantial progress has been made in establishing statewide trauma systems, which are seen as the prototype for regionalized care for other time-sensitive, emergency conditions such as stroke. Trauma systems provide a model of care that is consistent with the goals of the Affordable Care Act, which authorizes $100 million in annual grants to ensure the continued availability of trauma services. Full funding of these provisions is needed to stabilize statewide systems that are struggling to survive. We describe the components of a regionalized trauma system, review the evidence in support of this approach, and discuss the challenges to sustaining systems that are accountable and affordable.