2010 Census Public Use Microdata Areas (PUMA) Program

State Data Center Network:

The Census Bureau is currently drafting the 2010 Public Use Microdata Area (PUMA) delineation proposed criteria. These draft proposed criteria were developed based on internal meetings with key Census Bureau stakeholders, and with consideration of new challenges and issues associated with the use of PUMAs in the publication of annual American Community Survey (ACS) Public Use Microdata Sample (PUMS) data as well as in the publication of ACS estimates.

The Census Bureau will present the 2010 PUMA delineation proposed criteria at the upcoming State Data Center Annual Meeting (October 14-16, 2009) for discussion and comment. Subsequently, pending the approval of the Census Bureau’s Statistical Areas Committee, the Census Bureau will publish the 2010 PUMAs proposed criteria in the Federal Register for public comment. State Data Centers (SDCs) will use the final version of these criteria, as published in a forthcoming Federal Register, to delineate PUMAs for Census 2010 and the ACS.

For your consideration, the following represents a high level summary of the planned 2010 PUMA delineation proposed criteria:

1. PUMA types: One “level” of PUMAs will be delineated for the United States, Puerto Rico, Guam, and the U.S. Virgin Islands, as compared with two “levels” of PUMAs for Census 2000 (super-PUMAs and standard PUMAs). Additionally, place of work PUMAs (POW PUMAs) and migration PUMAs (MIG PUMAs) will be based on a single PUMA for county-based PUMAs or an aggregation of adjacent PUMAs for tract-based PUMAs. Note: All subsequent references to PUMAs in this document, unless preceded by “POW” or “MIG”, refer to these standard PUMAs.

2. Population Thresholds: Each PUMA must contain a minimum population of 100,000 both at the time of delineation and throughout the decade for the publication of ACS PUMS data and ACS estimates. For those areas currently experiencing population decline, or where population decline throughout the decade is expected, PUMAs should be initially delineated to include a population significantly higher than 100,000 persons to accommodate this change. Should the population of a PUMA fall significantly below the 100,000 person threshold, the PUMA will be combined with one or more adjacent PUMAs for ACS PUMS and ACS estimate publication.

3. PUMA Composition: All PUMA types (PUMAs, POW PUMAs and MIG PUMAs) must nest within states (i.e., may not cross state boundaries). PUMAs will be based on aggregations of counties and census tracts only. Incorporated places and MCDs will not be used as building blocks for 2010 PUMAs. Census tracts may be aggregated to approximate minor civil divisions, incorporated places, or census designated places.

Provided the PUMA meets the minimum population threshold:

a. One county may be designated as a PUMA

b. Two or more contiguous counties may be aggregated to create a PUMA

c. Contiguous census tracts may be aggregated to create a PUMA

• Tract-based PUMAs may cross county boundaries, provided that each PUMA-county part meets a minimum area and/or population threshold (TBD - The Census Bureau is currently determining an appropriate minimum area and population threshold for these areas, and will provide these minimum thresholds at the SDC Annual Meeting in October).

• Census tract aggregations may compose or approximate the extent of other types of geographic entities, including minor civil divisions, incorporated places, and census designated places.

4. PUMA contiguity In all cases, each PUMA must constitute a geographically contiguous area. Limited exceptions are presented here:

1. A PUMA may be noncontiguous if a county is noncontiguous.

2. A PUMA may be noncontiguous when it surrounds another whole PUMA, e.g., if census tracts define a PUMA that approximates an incorporated place or census designated place, a PUMA may be defined to encompass the area within the county surrounding the place

The Census Bureau also intends to propose additional guidelines to which delineation participants are strongly encouraged, but not required to, adhere.

For your consideration, the following represents a high level summary of the planned 2010 PUMA guidelines:

1. Wherever possible, each PUMA should comprise an area that is either entirely inside or entirely outside Core Based Statistical Areas

2. The Census Bureau recommends that the number of five-percent PUMAs be maximized, and that five-percent PUMAs should not contain more than 200,000 people, wherever possible, unless the PUMA is defined for an area that is or will be experiencing population decline.

We appreciate your interest in the 2010 PUMA delineation program, and look forward to discussing the planned proposed criteria with you at the SDC Annual Meeting in October 2009. Should you have more immediate questions please contact the Geographic Standards and Criteria Branch PUMA team at geo.puma@census.gov.