Before the development of medical expense insurance, patients were expected to pay health care costs out of their own pockets, under what is known as the fee-for-service business model. During the middle-to-late 20th century, traditional disability insurance evolved into modern health insurance programs. One major obstacle to this development was that early forms of comprehensive health insurance were enjoined by courts for violating the traditional ban on corporate practice of the professions by for-profit corporations.[66] State legislatures had to intervene and expressly legalize health insurance as an exception to that traditional rule. Today, most comprehensive private health insurance programs cover the cost of routine, preventive, and emergency health care procedures, and most prescription drugs (but this is not always the case).
The United States health care system relies heavily on private health insurance, which is the primary source of coverage for most Americans. As of 2012 about 61% of Americans had private health insurance according to the Centers for Disease Control and Prevention.[56] The Agency for Healthcare Research and Quality (AHRQ) found that in 2011, private insurance was billed for 12.2 million U.S. inpatient hospital stays and incurred approximately $112.5 billion in aggregate inpatient hospital costs (29% of the total national aggregate costs).[57] Public programs provide the primary source of coverage for most senior citizens and for low-income children and families who meet certain eligibility requirements. The primary public programs are Medicare, a federal social insurance program for seniors and certain disabled individuals; and Medicaid, funded jointly by the federal government and states but administered at the state level, which covers certain very low income children and their families. Together, Medicare and Medicaid accounted for approximately 63 percent of the national inpatient hospital costs in 2011.[57] SCHIP is a federal-state partnership that serves certain children and families who do not qualify for Medicaid but who cannot afford private coverage. Other public programs include military health benefits provided through TRICARE and the Veterans Health Administration and benefits provided through the Indian Health Service. Some states have additional programs for low-income individuals.[58]
Costs for employer-paid health insurance are rising rapidly: between 2001 and 2007, premiums for family coverage have increased 78%, while wages have risen 19% and inflation has risen 17%, according to a 2007 study by the Kaiser Family Foundation.[59] Employer costs have risen noticeably per hour worked, and vary significantly. In particular, average employer costs for health benefits vary by firm size and occupation. The cost per hour of health benefits is generally higher for workers in higher-wage occupations, but represent a smaller percentage of payroll.[60] The percentage of total compensation devoted to health benefits has been rising since the 1960s.[61] Average premiums, including both the employer and employee portions, were $4,704 for single coverage and $12,680 for family coverage in 2008.[58][62]
The term managed care is used to describe a variety of techniques intended to reduce the cost of health benefits and improve the quality of care. It is also used to describe organizations that use these techniques ("managed care organization").[96] Many of these techniques were pioneered by HMOs, but they are now used in a wide variety of private health insurance programs. Through the 1990s, managed care grew from about 25% US employees with employer-sponsored coverage to the vast majority.[97]
In the late 1990s federal legislation had been proposed to "create federally-recognized Association Health Plans which was then "referred to in some bills as 'Small Business Health Plans.'[79] The National Association of Insurance Commissioners (NAIC), which is the "standard-setting and regulatory of chief insurance regulators from all states, the District of Columbia and territories, cautioned against implementing AHPs citing "plan failures like we saw The Multiple Employer Welfare Arrangements (MEWAs) in the 1990s."[80] "[S]mall businesses in California such as dairy farmers, car dealers, and accountants created AHPs "to buy health insurance on the premise that a bigger pool of enrollees would get them a better deal."[81] A November 2017 article in the Los Angeles Times described how there were only 4 remaining AHPs in California. Many of the AHPs filed for bankruptcy, "sometimes in the wake of fraud." State legislators were forced to pass "sweeping changes in the 1990s" that almost made AHPs extinct.[81]
The bottom line? Uninsured people tend to be sicker and are more likely to die prematurely than their peers who do have health insurance.  Even adults who are young and healthy can benefit from preventive care, annual checkups and chronic disease management – be it for allergies, depression, asthma, diabetes or another type of condition. And women, in particular, benefit from gynecological and reproductive care.

The Blue Cross Blue Shield Association (BCBSA) is a federation of 38 separate health insurance organizations and companies in the United States. Combined, they directly or indirectly provide health insurance to over 100 million Americans.[92] BCBSA insurance companies are franchisees, independent of the association (and traditionally each other), offering insurance plans within defined regions under one or both of the association's brands. Blue Cross Blue Shield insurers offer some form of health insurance coverage in every U.S. state, and also act as administrators of Medicare in many states or regions of the United States, and provide coverage to state government employees as well as to federal government employees under a nationwide option of the Federal Employees Health Benefit Plan.[93]

The share of Americans without health insurance has been cut in half since 2013. Many of the reforms instituted by the Affordable Care Act of 2010 were designed to extend health care coverage to those without it; however, high cost growth continues unabated.[3] National health expenditures are projected to grow 4.7% per person per year from 2016 to 2025. Public healthcare spending was 29% of federal mandated spending in 1990 and 35% of it in 2000. It is also projected to be roughly half in 2025.[4]