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Zooming in on Health Reform: Understanding the Potential Impact of the ACA on Medicaid and the Uninsured at the Local Level

Nationwide, the Affordable Care Act (ACA) will expand Medicaid coverage to millions of people and substantially decrease the number of people without health insurance coverage. However, the impact of the law will vary by geographic region depending on current coverage patterns and socio-demographic/economic factors, among other things.

Use the interactive maps below to zoom in on your area and see how the number and composition of individuals enrolled in Medicaid or without insurance coverage could change if your state expands Medicaid. For additional analysis and a detailed methodology, please see the accompanying report.

How to Get Started

Select the population that you are interested in—either Medicaid Enrollment or the Uninsured Population—using the boxes at the top left of the screen. To see results for a particular geographic area, either a) enter a city, county, or zip code in the search box and hit “Enter” or b) using your mouse or the +/- buttons at the top right of the screen, zoom in and click on the map. Once you’ve viewed results for a given location, you can use the “Compare” feature on the left to compare that location to another, using the same steps to select your comparison location. For more details or tips, see FAQ below.

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Source: Urban Institute estimates based on ACS-HIPSM, prepared for the Kaiser Commission on Medicaid and the Uninsured, 2013.

Frequently Asked Questions

Using the Interactive Tool:

How do I find results for my area?

To see data for a particular geographic area, either a) type a location in the search box and hit "Enter" or b) zoom and click on the map using your mouse or the +/- buttons at the top right of the screen. Summary data will appear in a box at the bottom of the map. Once you've viewed results for a given location, you can use the “Compare” feature on the left to compare that location to another, using the same steps to select your comparison location. To start over, hit the “Reset” button on the left or refresh the page.

How do I view additional characteristics other than age?

Once an area is selected, the results box will appear at the bottom of the map. The left side of the box displays overall results, including both the number and the percentage of the population who is either enrolled in Medicaid or is uninsured, both before and after ACA implementation. The right side of the box displays the characteristics of the population enrolled in Medicaid or uninsured before and after the ACA. The default characteristic is age. To view other characteristics, click on the variable of interest below the bar graphs. For definitions and methodologies of the characteristics please see State and Local Coverage Changes Under Full Implementation of the Affordable Care Act.

How do I compare two areas?

Results are always presented in comparison to another geographic area, usually the larger geographic area within which the selected area is contained (for example, the default comparison for a local area is that local area’s state). To change the comparison after you’ve viewed results for an area, click the “Compare” button below the search box. After the “Compare” text is highlighted, select a comparison location either by zooming/clicking on the map or typing the comparison location in the search box.

What do "Selected" and "Compare" mean?

The results box displays characteristics data for two geographies. The selected geography is the first location selected and is represented by yellow bars and text. The compare data is the second location selected and represented by grey bars and text. To change the comparison location, see "How do I compare two areas? " above.

What is a local area?

A local area is a constructed geography created from counties, groupings of counties, or areas within counties. More densely-populated local areas are generally geographically smaller than non-densely populated areas. Local areas are non-overlapping and cover the entire United States. Local areas are named based on the three largest places in that local area or, when composed of a single county, the county name. For more detail on how local areas were constructed, see State and Local Coverage Changes Under Full Implementation of the Affordable Care Act.

How am I supposed to know what local area I want?

The search tool or zoom function will automatically link your desired city, county, zip code, or other geographic unit to its matching local area.

Why is my local area so big?

Local areas were constructed so as to have a large enough population to enable reliable estimates to be produced. Rural or non-densely populated regions will have fewer local areas.

Why is there no bar for some of the characteristics?

Some local areas or counties do not have a large enough population to enable reliable estimates for certain characteristics. When the data is suppressed, no bar will appear.

What are selected counties?

Selected counties are counties for which the data source underlying this analysis has available county-level data. Data for all counties is not available. Selected counties account for 60 percent of the total population in the United States.

Why is my county showing up when I type in my zip code?

The tool will pull up the geographic unit that most closely matches your entry. Zip code level data is not available, so the county or local area in which the zip code is located is displayed.

How do I start over?

If you would like to begin again, either click on the reset button under the search box or refresh the webpage.

How can I get the map to print?

The best way to print the map is to take a screen shot or screen capture of the map and print that image.

Who do I contact if I have problems or questions?

For problems or questions please contact us at

Understanding the Data: 

What is the source of this data?

This analysis uses the Urban Institute’s American Community Survey-based Health Insurance Policy Simulation Model (ACS-HIPSM). This model simulates decisions of individuals in response to policy changes, such as Medicaid expansions, new health insurance options, subsidies for the purchase of health insurance, and insurance market reforms, using data from the American Community Survey (ACS). For more details on the ACS-HIPSM and the methods underlying this analysis, see

For what year is the data?

The estimates represent changes to the Medicaid and uninsured populations as if the coverage provisions of the ACA were fully implemented in 2011. The model was built based on pooled ACS data from 2008, 2009, and 2010; three years of ACS data are combined to achieve sufficient precision at the state and local level. The pooled data is reweighted so that the distributions of demographic, employment, income, and health insurance coverage in the merged file match those of 2011 estimates published by the Census Bureau.

Is the underlying data for the map available to download or in table form?

At this time, the data is not available to download or in any other form beyond the map.

Does the data represent the actual number of people who will be enrolled in Medicaid or who will remain uninsured?

The data represents the anticipated changes in Medicaid enrollment and the uninsured before and after the ACA, based on a micro-simulation model. The micro-simulation model assesses the relative desirability of the health insurance options available to each individual and family under reform and takes into account a number of factors such as premiums and out-of-pocket health care costs for available insurance products, health care risk, whether or not the individual mandate would apply to them, and family disposable income. As with all projections of ACA coverage impacts, there is uncertainty of actual outcomes due to difficulties associated with predicting take-up of different types of coverage under the ACA and other behavioral responses as well as with respect to federal and state actions that could affect a number of implementation issues. Most importantly, these results assume state participation in the ACA Medicaid expansion.

Does the data include children? The elderly? Undocumented non-citizens?

The data includes children (ages 0-18) but does not include individuals over the age of 64. The data uses imputed estimates of undocumented non-citizens and accounts for their eligibility.

Does the data account for states that are not participating in the Medicaid expansion?

This data represents Medicaid enrollment and the reduction in the uninsured if all states were participating in the Medicaid expansion. No additional estimates were made with regards to expansion decisions by states.

Do the Medicaid numbers include CHIP? Dually eligible individuals?

The Medicaid numbers do include CHIP enrollment. Data does include dually eligible individuals under age 65 as well.

Does the map have data on private insurance in the exchanges?

This interactive tool does not provide data on changes in private insurance coverage under the ACA. However, estimates of changes in the uninsured account for expansions of both Medicaid coverage and coverage through private insurance.

How do these results relate to other state and local data?

Because “local areas” were constructed for this analysis, they will not match geographic units in other data sets. State and county-level estimates are based on current county and state definitions, similar to those used in other data sources.

Why do these numbers not match other estimates of ACA impacts?

This data uses the American Community Survey estimates in combination with the Urban Institute’s HIPSM model. Estimates may vary from analyses that use other data sources or models. Overall estimates are consistent with other sources.

How should I cite this data/analysis?

The suggested citation for this analysis is: Urban Institute estimates based on ACS-HIPSM, prepared for the Kaiser Commission on Medicaid and the Uninsured, 2013.

Who can I contact with questions regarding the map or the data?

For questions regarding the map or the data please contact us at