Accident insurance was first offered in the United States by the Franklin Health Assurance Company of Massachusetts. This firm, founded in 1850, offered insurance against injuries arising from railroad and steamboat accidents. Sixty organizations were offering accident insurance in the US by 1866, but the industry consolidated rapidly soon thereafter. While there were earlier experiments, sickness coverage in the US effectively dates from 1890. The first employer-sponsored group disability policy was issued in 1911, but this plan's primary purpose was replacing wages lost because the worker was unable to work, not medical expenses.[19]
In 2006, a new system of health insurance came into force in the Netherlands. This new system avoids the two pitfalls of adverse selection and moral hazard associated with traditional forms of health insurance by using a combination of regulation and an insurance equalization pool. Moral hazard is avoided by mandating that insurance companies provide at least one policy which meets a government set minimum standard level of coverage, and all adult residents are obliged by law to purchase this coverage from an insurance company of their choice. All insurance companies receive funds from the equalization pool to help cover the cost of this government-mandated coverage. This pool is run by a regulator which collects salary-based contributions from employers, which make up about 50% of all health care funding, and funding from the government to cover people who cannot afford health care, which makes up an additional 5%.[31]
The US health insurance market is highly concentrated, as leading insurers have carried out over 400 mergers from the mid-1990s to the mid-2000s (decade). In 2000, the two largest health insurers (Aetna and UnitedHealth Group) had total membership of 32 million. By 2006 the top two insurers, WellPoint (now Anthem) and UnitedHealth, had total membership of 67 million. The two companies together had more than 36% of the national market for commercial health insurance. The AMA has said that it "has long been concerned about the impact of consolidated markets on patient care." A 2007 AMA study found that in 299 of the 313 markets surveyed, one health plan accounted for at least 30% of the combined health maintenance organization (HMO)/preferred provider organization (PPO) market. In 90% of markets, the largest insurer controls at least 30% of the market, and the largest insurer controls more than 50% of the market in 54% of metropolitan areas.[116] The US Department of Justice has recognized this percentage of market control as conferring substantial monopsony power in the relations between insurer and physicians.[117]
Out-of-pocket maximum: Similar to coverage limits, except that in this case, the insured person's payment obligation ends when they reach the out-of-pocket maximum, and health insurance pays all further covered costs. Out-of-pocket maximum can be limited to a specific benefit category (such as prescription drugs) or can apply to all coverage provided during a specific benefit year.
Medicaid was instituted for the very poor in 1965. Since enrollees must pass a means test, Medicaid is a social welfare or social protection program rather than a social insurance program. Despite its establishment, the percentage of US residents who lack any form of health insurance has increased since 1994.[51] It has been reported that the number of physicians accepting Medicaid has decreased in recent years because of lower reimbursement rates.[52]

Coinsurance: Instead of, or in addition to, paying a fixed amount up front (a co-payment), the co-insurance is a percentage of the total cost that insured person may also pay. For example, the member might have to pay 20% of the cost of a surgery over and above a co-payment, while the insurance company pays the other 80%. If there is an upper limit on coinsurance, the policy-holder could end up owing very little, or a great deal, depending on the actual costs of the services they obtain.

In the run-up to the 2016 Democratic National Convention, the Democratic Platform Committee approved a plank supporting the addition of a public option onto the Affordable Care Act.[14] The decision was seen as a compromise measure between the Hillary Clinton campaign who during the 2016 presidential primaries advocated for keeping and reforming the ACA, and the Bernie Sanders campaign who advocated for repealing and replacing the ACA with a single-payer Medicare for All program. The Clinton campaign stated shortly before the plank was added that as president Clinton would "pursue efforts to give Americans in every state in the country the choice of a public-option insurance plan", while Bernie Sanders applauded the decision to "see that all Americans have the right to choose a public option in their health care exchange, which will lower the cost of healthcare".[15][16] The call was echoed by President Obama, who in an article for the American Medical Association stated that Congress "should revisit a public plan to compete alongside private insurers in areas of the country where competition is limited."[17]
Health insurance in the United States is any program that helps pay for medical expenses, whether through privately purchased insurance, social insurance, or a social welfare program funded by the government.[1] Synonyms for this usage include "health coverage", "health care coverage", and "health benefits". In a more technical sense, the term "health insurance" is used to describe any form of insurance providing protection against the costs of medical services. This usage includes private insurance and social insurance programs such as Medicare, which pools resources and spreads the financial risk associated with major medical expenses across the entire population to protect everyone, as well as social welfare programs like Medicaid and the Children's Health Insurance Program, which both provide assistance to people who cannot afford health coverage.