Pivotal moments in American health care history:

1798: The Act for the Relief of Sick and Disabled Seamen in 1798 marks the beginning of federal involvement in health care.

1854: President Franklin Pierce vetoes a national mental health bill on the basis that it would be unconstitutional to regard health as anything but a private matter.

1912: Former President Theodore Roosevelt campaigns on a platform calling for a single national health service.

1920: The Snyder Act of 1920 is the first federal legislation to deal with health care for Native Americans, setting up what became the Indian Health Service.

1921: The Maternity and Infancy Act of 1921 (Sheppard-Towner Act) provides grants to states to plan maternal and child health services. Bill serves as a prototype for federal grants-in-aid to the states in the area of health.

1924: The Veterans Act of 1924 codifies and extends federal responsibilities for health care services to vets, who receive aid if they are injured in the line of service.

1932: The Committee on the Costs of Medical Care report raises concerns about the costs of health care and the number of people lacking medical services.

1935: The Social Security Act, providing pensions and other benefits to the elderly, is signed into law by President Franklin Delano Roosevelt.

1937: The Technical Committee on Medical Care is convened to advance health care reform.

1938: A national health Conference proposes federal aid to the states to expand public health, maternal and children's services and hospital facilities.

1939: The Wagner National Health Act of 1939, FDR's second push for national health insurance, fails as Southern Democrats align with Republicans to oppose government expansion.

1943: The National War Labor Board declares employer contributions for health insurance to be tax free, encouraging companies to offer insurance to attract workers.

1943: The Wagner-Murray-Dingell bill is introduced, calling for broad additions to the Social Security Act, including health insurance measures. The bill never came to a vote in Congress. A revised version was introduced in May 1945 but was never acted upon.

1945: President Harry Truman recommends a national health insurance program during a special address to Congress. The McCarran-Fergurson Act of 1945 exempts the insurance industry from federal antitrust legislation.

1946: The National Health Policy Hospital Survey and Construction Act of 1946 provides grants to states to inventory and survey existing hospital and public health care facilities and plan new ones.

1948: Truman's National Health Insurance Initiative fails after the American Medical Association criticizes it, and some Republicans compare it to communism.

1951: Truman creates, by executive order, the President's Commission on the Health Needs of the Nation to determine the nation's health requirements, both immediate and long term.

1952: Presidential candidate Dwight D. Eisenhower campaigns against national health insurance.

1954: President Eisenhower proposes a plan of federal reinsurance for any private company as protection against heavy losses resulting from health insurance. After the first five years, the program would become self-financing with money derived from premiums paid by the insurance companies. The House soundly rejects it.

1959: A bill is introduced by Rep. Aime J. Forand, D-R.I., to provide hospital, surgical and nursing home benefits for old-age and survivors insurance beneficiaries using the Social Security administrative mechanism. The program is to be financed by an increase in the Social Security tax. Bill fails.

1960: Legislation is enacted establishing limited medical assistance for the aged through the Social Security program. The act also provides aid to the states to help "medically indigent" people 65 or older. Participation by states is optional; 25 take part.

1962: President John F. Kennedy renews his 1961 request that the old-age, survivors and disability provisions of the Social Security Act be amended to provide health insurance protection for the aged.

1965: President Lyndon B. Johnson signs into law the landmark federal health insurance programs known as Medicare and Medicaid.

1971: Sen. Edward M. Kennedy, D-Mass., offers his Health Security Act, calling for a universal single-player plan to be financed through payroll taxes. President Richard Nixon later advances his National Health Insurance Partnership Act. It would preserve private insurance but require businesses to provide coverage to employees or make payments to a government-run fund. It also endorses the concept of health maintenance organizations. The bill fails.

1973: Legislation is enacted to encourage development of health maintenance organizations.

1974: Nixon proposes his Comprehensive Health Insurance Plan calling for universal coverage, voluntary employer participation and a program for the working poor and the unemployed, replacing Medicaid. Organized labor lobbied successfully to kill the plan.

1977: The Health Care Financing Administration is created to manage Medicare and Medicaid separately from the Social Security Administration.

1979: Sen. Kennedy proposes that private insurance plans compete for customers who would receive a card to use for hospital and physician's care. President Jimmy Carter's plan, released a month later, proposes that businesses provide a minimum package of benefits, that public coverage for the poor and aged be expanded and that a new public corporation created to sell coverage to everyone else. Neither proposal makes it through Congress.

1985: COBRA (the Consolidated Omnibus Budget Reconciliation Act), signed into law by President Ronald Reagan, mandates an insurance program giving some employees the ability to continue health insurance coverage from their workplace after leaving the job.

1988: The Medicare Catastrophic Coverage Act provides the largest expansion of benefits since the creation of the program and increases premiums. The act is repealed before provisions go into effect. The McKinney Act is signed into law, providing health care to the homeless.

1990: The Americans with Disabilities Act provides a broad range of protections for the disabled.

1993: President Bill Clinton proposes a reworking of the health care system, aiming squarely for universal coverage. But he cannot persuade fellow Democrats in control of Congress to adopt it.

1996: The Health Insurance Portability and Accountability Act improves continuity of health insurance coverage in group and individual markets for people who lose their job.

1997: The State Children's Health Insurance Program is established to help provide medical care to children in low-income families that are not poor enough to qualify for Medicaid.

2003: President George W. Bush signs a law adding prescription drugs to Medicare.

Jan. 19, 2010: Republican Scott Brown's upset in the Massachusetts Senate seat opened by Sen. Kennedy's death deprives Democrats of the 60 votes needed to move legislation forward. The effort to reconcile health overhaul bills passed by the House and Senate is stalled.

March 2010: Democratic leaders in Congress employ parliamentary maneuvers in hopes of enabling passage of Obama's plan with a simple majority in the Senate. A showdown vote is set in the House for today.