New data released by the U.S. Census Bureau today show that the number of people without health insurance declined by 1.3 million in 2011, falling to 48.6 million people. (Exhibit 1). This is excellent news—the number of uninsured has increased by 12 million people over the past decade, and the latest numbers suggest an important turning point in this upward trend. The decline in uninsured Americans in 2011 was the largest one-year drop in the past decade. 
Young adults made strong gains in coverage, continuing a trend that began in 2010 with the passage of the Affordable Care Act. The percentage of uninsured young adults ages 19 to 25 without health insurance declined by 2.2 percentage points in 2011, to 27.7 percent, down from 29.8 percent in 2010 and 31.4 percent in 2009 (Exhibit 2). This nearly 4 percentage point decline in the share of young adults who lack health insurance over the past two years reverses the growth in the uninsured in this age group over the past decade, and is likely attributable to the Affordable Care Act; young adults under age 26 may now stay on or join their parents' health plans. About 1 million more young adults had insurance coverage in 2011 compared with 2009, prior to the passage of the law.
Public insurance coverage, including Medicaid, Medicare, and the Children's Health Insurance Program (CHIP), continues to be an important source of coverage for people of all ages without job-based health insurance. Nearly 100 million people had health insurance through government programs, including the military's Tricare program, in 2011, up from 95.5 million people in 2010. The percent of people covered by Medicaid climbed to 16.5 percent in 2011, or 50.8 million, up from 15.8 percent or 48.5 million in 2010 (Exhibit 4). The increase in Medicaid coverage helped people of all ages, but children and older adults particularly benefitted. More than one-third (35.6%) of children under age 18 are now insured through Medicaid or CHIP. And an additional 1.5 million people age 65 and over, the post–World War II "boomers," enrolled in Medicare. 
Families with incomes under $50,000 continue to be the income group most likely to lack health insurance. A quarter (25.4%) of people with incomes under $25,000 were without health insurance in 2011 and more than one of five (21.5%) of those in families with incomes between $25,000 and $50,000 were uninsured. Families in this income range will realize the greatest benefits from the full implementation of the Affordable Care Act in January 2014, through a substantial expansion in eligibility for Medicaid and premium tax credits to offset the cost of private health plans to be sold through the new state insurance exchanges.
Massachusetts led the nation in coverage, with just 4.5 percent of its total population, including those over age 65, without health insurance (Exhibit 5). This stands in stark contrast to Texas, where 24.2 percent of the total population is without health insurance, the highest rate in the nation. Massachusetts implemented a universal health insurance system in 2006 much like the Affordable Care Act and has since experienced a steady expansion in insurance coverage across its population.
Looking Forward
The decline in the number of people without health insurance in 2011 reflects the effects of the Affordable Care Act among young adults, stabilization in the share of people with employer-based coverage, and the essential role of public insurance programs in the nation's health system. Medicare, Medicaid, and the Children's Health Insurance Program are critical sources of coverage for Americans across the age spectrum, providing health insurance to nearly 100 million people in 2011. The gain in coverage made by young adults over the past two years is a preview of the sweeping changes we will see after the state insurance