Unlike the world’s other advanced democracies, the United States faces this vortex of pressures without first having institutionalized a system for universal health insurance. Moreover, it confronts these forces in a political context marked by intense and basic ideological disagreement over government’s proper role in the health care arena. As befits a fragmented political system with a culture leery of centralized authority, the United States has long depended on an messy, decentralized mix of public and private sources to provide health insurance. The system rests on a health insurance regime that features a dizzying array of federal and state policies---direct government subsidies, regulation, tax incentives, and more. This regime has yielded a health care sector that plays a huge role in the nation’s economy, with health expenditures representing some 18 percent of gross domestic product, Federal, state, and local government account for about half of all health spending.