Medicare was signed into law on July 30, 1965, and within a year seniors were receiving coverage. President Barack Obama signed the Affordable Care Act on March 23, 2010, and the uninsured start getting coverage more than three years later on Jan. 1, 2014. Some key dates in the saga of Obama's signature legislation:
March 23, 2010 — Obama signs the Patient Protection and Affordable Care Act (ACA). Democrats hail an achievement their party pursued for more than 50 years — individuals' right to health care. The law requires most Americans to carry health insurance starting in 2014, and bars insurers from turning away the sick. It creates state markets for middle-class people without workplace coverage to purchase private insurance, subsidized with tax credits. It expands Medicaid for the low-income uninsured. After long debate, the legislation barely passed a divided Congress, with no Republican support. Public opinion is split.
March 29, 2010 —Health and Human Services Secretary Kathleen Sebelius and the health insurance industry reach a deal to fix the first glitch emerging from the complex legislation: vague language that compromised a guarantee that children with pre-existing medical conditions could get coverage right away.
Fall 2010 — During open enrollment, most health insurance plans begin offering coverage to young adults up to age 26 on a parent's policy. The popular early provision expanded coverage to more than 3 million people. Plans also begin covering preventive services at no charge.
Nov. 2, 2010 — Democrats lose control of the House in midterm congressional elections. Republicans campaigned on a vow to "repeal and replace" the law.
Jan. 19, 2011 — The Republican-led House votes to repeal "Obamacare," but the drive falters in the Senate, where Democrats retain a majority. Since then, the House has repeatedly voted to repeal, defund or in some way scale back the law. Republican replacement legislation has been stymied by divisions within the party.
Jan. 31, 2011 — Florida U.S. District Judge Roger Vinson rules that the ACA is unconstitutional. The lawsuit by 26 states would ultimately reach the Supreme Court.
April 5, 2011 — Congress votes to repeal an unpopular tax requirement in the law that would have forced millions of businesses to file tax forms for every vendor selling them more than $600 in goods. Agreeing to sign it, Obama says he'll make fixes as warranted.
June 21, 2011 — The Obama administration says it will look for fixes to another glitch, a twist that would have let several million middle-class people receiving Social Security payments get nearly free insurance meant for the poor. Enacted later, the fix saved an estimated $13 billion over 10 years.
Summer 2011 — Seniors hitting Medicare's prescription drug coverage gap start getting a 50 percent discount on brand name medications, part of the health care law's gradual closing of the "doughnut hole." In 2011, the typical senior in the gap saved about $600 on bills averaging $1,500.
Aug. 1, 2011 — Sebelius, on the recommendation of an expert panel, declares that most health plans will have to cover birth control for women as a preventive service, free of charge. The coverage became available in 2013, as lawsuits proliferated from groups and businesses objecting on religious grounds.
Oct. 14, 2011 — Sebelius pulls the plug on the ACA's long-term care insurance program, because of doubts over its long-term financial solvency. The program was a priority of the late Massachusetts Democratic Sen. Edward M. Kennedy.
Nov. 14, 2011 — The Supreme Court announces it will hear the constitutional challenge to the ACA, setting the stage for an election-year decision.
Fall/Winter 2011-2012 — Republican presidential candidates are united in their determination to repeal "Obamacare." Former Massachusetts Gov. Mitt Romney, whose state health law was seen as a model for Obama's, says he'd sign an executive order on Day One of his presidency granting a waiver to all 50 states.
March 26-28, 2012 — Supreme Court holds three days of oral arguments on the ACA. The administration's lawyer fumbles his defense, and opponents feel momentum breaking their way.
June 28, 2012 — With the unlikely support of conservative Chief Justice John Roberts, the Supreme Court upholds the law's core requirement that most Americans carry health insurance, ruling that the penalties to enforce it are a tax Congress is authorized to levy. But the court allows states to individually opt out of the Medicaid expansion, which accounts for about half the law's coverage expansion.
Summer 2012 — Employers and consumers receive more than $1 billion in rebates from their insurers, which are required under the ACA to spend at least 80 cents of every premium dollar on medical expenses and quality improvement, or refund the difference.
Nov. 6, 2012 — Obama is re-elected to a second term, deflating Republican repeal hopes.
Nov. 8, 2012 — House Speaker John Boehner says in an interview that "Obamacare is the law of the land." His spokesman quickly adds that the Ohio Republican remains "committed to full repeal."
Jan. 1, 2013 — Tax increases to finance the ACA take effect on about 2.5 million households, individuals making more than $200,000 per year and couples over $250,000.
Winter/Spring, 2013 — States decide whether they'll run the new insurance markets and expand their Medicaid programs. The ACA advances mainly in blue states, while most Republican-led states continue to oppose the law.
April 30, 2013 — Obama administration unveils simplified forms consumers will use to apply for health insurance and financial assistance to pay their premiums. The first version was criticized as too complicated.
July 2, 2013 — In a surprise, the White House announces a one-year delay — until 2015 — of the law's requirement that companies with 50 or more workers must provide affordable coverage or pay fines. The administration says it's trying to iron out burdensome reporting requirements.
Oct. 1, 2013 — Online insurance markets are scheduled to open in every state. Consumers must sign up by Dec. 15 for coverage to take effect Jan. 1.