Healthcare in the United States is largely provided by private sector healthcare facilities, and paid for by a combination of public programs, county indigent health care programs, private insurance, and out-of-pocket payments. The U.S. is the only developed country without a system of universal healthcare, and, as of 2023, 7.9% of the population does not have health insurance. The United States spends more on healthcare than any other country, both in absolute terms and as a percentage of GDP; however, this expenditure does not necessarily translate into better overall health outcomes compared to other developed nations. In 2022, the United States spent approximately 17.8% of its Gross Domestic Product (GDP) on healthcare, significantly higher than the average of 11.5% among other high-income countries. Coverage varies widely across the population, with certain groups, such as the elderly, disabled and low-income individuals receiving more comprehensive care through government programs such as Medicaid and Medicare.

The U.S. healthcare system has been the subject of significant political debate and reform efforts, particularly in the areas of healthcare costs, insurance coverage, and the quality of care. Legislation such as the Affordable Care Act of 2010 has sought to address some of these issues, though challenges remain. Uninsured rates have fluctuated over time, and disparities in access to care exist based on factors such as income, race, and geographical location. The private insurance model predominates, and employer-sponsored insurance is a common way for individuals to obtain coverage.

The complex nature of the system, as well as its high costs, has led to ongoing discussions about the future of healthcare in the United States. At the same time, the United States is a global leader in medical innovation, measured either in terms of revenue or the number of new drugs and medical devices introduced. The Foundation for Research on Equal Opportunity concluded that the United States dominates science and technology, which "was on full display during the COVID-19 pandemic, as the U.S. government [delivered] coronavirus vaccines far faster than anyone had ever done before", but lags behind in fiscal sustainability, with "[government] spending ... growing at an unsustainable rate".

In the early 20th century, advances in medical technology and a focus on public health contributed to a shift in healthcare. The American Medical Association (AMA) worked to standardize medical education, and the introduction of employer-sponsored insurance plans marked the beginning of the modern health insurance system. More people were starting to get involved in healthcare like state actors, other professionals/practitioners, patients and clients, the judiciary, and business interests and employers. They had interest in medical regulations of professionals to ensure that services were provided by trained and educated people to minimize harm. The post–World War II era saw a significant expansion in healthcare where more opportunities were offered to increase accessibility of services. The passage of the Hill–Burton Act in 1946 provided federal funding for hospital construction, and Medicare and Medicaid were established in 1965 to provide healthcare coverage to the elderly and low-income populations, respectively.

The healthcare system in the United States can be traced back to the Colonial Era. Community-oriented care was typical, with families and neighbors providing assistance to the sick. During the 19th century, the practice of medicine began to professionalize, following the "Anglo-American model" where these new medical professionals were empowered by the state to govern their own affairs, leading to various collaborations to acquire status and win legislation granting them the power to self-regulate. The establishment of medical schools and professional organizations led to standardized training and certification processes for doctors. Despite this progress, healthcare services remained disparate, particularly between urban and rural areas. The concept of hospitals as institutions for the sick began to take root, leading to the foundation of many public and private hospitals.^{[page needed]}

The latter part of the 20th century saw continued evolution in healthcare policy, technology, and delivery. Following the Stabilization Act of 1942, employers, unable to provide higher salaries to attract or retain employees, began to offer insurance plans, including healthcare packages, as a benefit in kind, thereby beginning the practice of employer-sponsored health insurance, a practice that is cemented into the work culture of today. The Health Maintenance Organization Act of 1973 encouraged the development of managed care, while advances in medical technology revolutionized treatment. In the 21st century, the Affordable Care Act (ACA) was passed in 2010, extending healthcare coverage to millions of uninsured Americans and implementing reforms aimed at improving quality and reducing costs.

According to a statistical brief by the Healthcare Cost and Utilization Project (HCUP), there were 35.7 million hospitalizations in 2016, a significant decrease from the 38.6 million in 2011. For every 1,000 in the population, there was an average of 104.2 stays and each stay averaged $11,700 (equivalent to $15,329 in 2024), an increase from the $10,400 (equivalent to $14,244 in 2024) cost per stay in 2012. Approximately 7.6% of the population had overnight stays in 2017, each stay lasting an average of 4.6 days.

A study by the National Institutes of Health reported that the lifetime per capita expenditure at birth, using the year 2000 dollars, showed a large difference between the healthcare costs of females ($361,192, equivalent to $659,498 in 2024) and males ($268,679, equivalent to $490,579 in 2024). A large portion of this cost difference is in the shorter lifespan of men, but, even after adjustment for age (assuming men live as long as women), there still is a 20% difference in lifetime healthcare expenditures.