A Look at Early ACA Implementation

First year of the Affordable Care Act's (ACA) implementation led to a large drop in uninsured adults.

The Issue

States that expanded Medicaid saw larger drops in the uninsured than nonexpansion states, with seven in 10 Medicaid-eligible adults participating in the program in 2014.

Key Findings

During the first year of ACA implementation:

  • Number of uninsured adults dropped by more than 8 million.

  • Seven in 10 eligible adults without another source of coverage were enrolled in Medicaid in 2014.

  • Overall, the percentage of non-elderly uninsured adults dropped from 21.0 percent in 2013 to 16.5 percent in 2014.


The majority of the 8.3 million uninsured adults who were eligible for Medicaid but not enrolled in 2014 resided in Medicaid expansion states. Given subsequent increases in Medicaid enrollment reported by the Department of Health and Human Services, it is likely that the number of uninsured who are eligible for Medicaid but not enrolled has also decreased since 2014.

About the Urban Institute

The nonprofit Urban Institute is dedicated to elevating the debate on social and economic policy. For nearly five decades, Urban scholars have conducted research and offered evidence-based solutions that improve lives and strengthen communities across a rapidly urbanizing world. Their objective research helps expand opportunities for all, reduce hardship among the most vulnerable, and strengthen the effectiveness of the public sector. Visit the Urban Institute’s Health Policy Center for more information specific to its staff and its recent research.