Affordable Care Act Signed — Most Significant US Healthcare Expansion Since Medicare (1965)

President Obama signed the Affordable Care Act on March 23, 2010, establishing insurance exchanges, expanding Medicaid, mandating coverage of pre-existing conditions, allowing dependents to remain on parents' plans until 26, and requiring most Americans to carry insurance. By 2016, approximately 20 million previously uninsured Americans gained coverage. Not a single Republican voted for the law. The Supreme Court upheld it 5-4 in 2012 (NFIB v. Sebelius) and 7-2 in 2021 (California v. Texas).