The U.S. Census Bureau’s 2011 American Community Survey released last week carried a few grim data points, such as a climb in the number of people in Illinois who live in poverty.

However, there is one critical piece of good news for Illinois and the country – the number of people without health care is slightly down due to an initial step in implementing the landmark 2010 Affordable Care Act.

A report released Friday by the Washington, D.C. Center for Budget and Policy Priorities (CBBP) using ACS survey data found that the number of people without health care nationally dropped from 16.3 percent to 15.7 percent. The number of Illinoisans without health care declined from 13.8 percent to 13.1 percent, or 1.66 million state residents.

The reason for the decline is simple. Under ACA, any American citizen who is 26 years-old or younger can stay on their parent’s insurance plan. Previously, young adults were kicked off their parent’s insurance at 19 years of age or when they left college.

According to the report, the number of 18 to 24 year-old Illinois residents with health insurance increased 3.5 percent to 64.7 percent, while the number 25 to 64 year-old state residents with insurance actually decreased 0.5 percent to 71.1 percent.

The U.S. Supreme Court decision in June to uphold ACA not only means that young adults may continue to use their parent’s health care, but it also should give Illinois more far-reaching policies toward the law’s ultimate aim of universal health coverage. Study co-author Matt Broaddus, a research analyst at CBPP, says that he anticipates a “dramatic shift” in insurance coverage rates starting in 2014 when much of the ACA law kicks in.

Governor Pat Quinn’s office estimates that 500,000 state residents will begin to obtain health care in 2014, when the state is expected to cover all adults below 133 percent of the federal poverty level through a Medicaid expansion paid for entirely by the federal government.

The state must first pass legislation enabling it to expand Medicaid, following a series of laws passed this May that cut funding for the federal-state health program for the poor, elderly, and disabled.

Indeed, the number of uninsured Illinois residents may go up in the next couple of years before declining in 2014 due to the ACA.