Introduction

A Public Use Microdata Area (PUMA) is a geographic unit defined by the US Census Bureau that contains a minimum of 100,000 people, is non-overlapping, and covers the entire United States, Puerto Rico, and Guam. PUMAs are used to make decennial census and American Community Survey (ACS) data accessible through the Public Use Microdata Sample (PUMS) files, which are detailed, anonymized datasets of individual records. By providing these smaller, more granular geographical areas, PUMAs allow data users to create custom tables, perform statistical analysis, and develop new variables to explore detailed demographic information without compromising individual privacy. The delineation of new PUMAs occurs after the completion of the decennial census as part of a program involving the State Data Centers (SDCs). Decennial census population counts and updated census tracts are critical inputs into the delineation process.

How PUMAs Work

• Anonymized Data: PUMS files contain individual-level data, but to protect confidentiality, all personally identifiable information is removed.
• Geographic Granularity: PUMAs are defined to be large enough to protect privacy while still offering more geographic detail than larger aggregated areas.
• Customization: Data users can aggregate PUMA data to create custom estimates for their specific needs, allowing for greater flexibility in analysis.
• Population Threshold: PUMAs are defined by a minimum population size (100,000) to ensure that individual records cannot be identified, a threshold that the Census Bureau maintains by combining PUMAs if their population falls too low.
• State-Based: PUMAs are non-overlapping geographic areas contained within a single state.

Who Uses PUMAs

• Researchers: PUMAs enable researchers to analyze demographic trends and relationships between variables at a more detailed geographic level than is typically available in standard census products.
• State and Local Governments: These entities can use PUMAs to create custom tables and develop their own data estimates for local planning and policy-making.
• Academics: PUMAs provide a valuable resource for students and academics to perform statistical analysis and create data visualizations.

The map and table below give geographic data on Alabama's 39 PUMAs. The land and water areas are given in square miles.

Map

In the map below, the census-designated central points can be added as a point layer.

Table

In the table below, click on a row to highlight the corresponding PUMA in the map above. Click the row again to de-select.