Bureau of the Census, Commerce.
Notice of final criteria and program implementation.
Block groups are statistical geographic subdivisions of a census tract defined for the tabulation and presentation of data from the decennial census and selected other statistical programs. Block groups also will be used to tabulate and publish estimates from the American Community Survey (ACS) after 2020 and potentially data from other Bureau of the Census (Census Bureau) censuses and surveys. The Census Bureau is publishing this notice in the Federal Register to announce final criteria for defining block groups for the 2020 Census Participant Statistical Areas Program (PSAP). In addition to block groups, the program also encompasses the review and update of census tracts, census designated places, and census county divisions.
This notice's final criteria will be applicable on December 13, 2018.
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FOR FURTHER INFORMATION CONTACT:
Requests for additional information on this program should be directed to Vincent Osier at the Geographic Standards, Criteria, and Quality Branch, Geography Division, U.S. Census Bureau, via email at email@example.com or by telephone at 301-763-3056.
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Start Supplemental Information
Block groups are statistical geographic subdivisions of a census tract defined for the tabulation and presentation of data from the decennial census and selected other statistical programs. Block groups also will be used to tabulate and publish estimates from the American Community Survey (ACS) 
after 2020 and potentially data from other Bureau of the Census (Census Bureau) censuses and surveys.
The Census Bureau is publishing this notice in the Federal Register to announce final criteria for defining block groups for the 2020 Census. In addition to providing final criteria for block groups, this notice also contains a summary of comments received in response to proposed criteria published in the Federal Register on February 15, 2018 (83 FR 6937), as well as the Census Bureau's response to those comments. After publication of this final criteria in the Federal Register, the Census Bureau will offer designated governments or organizations an opportunity to review and, if necessary, suggest updates to the boundaries and attributes of the block groups in their geographic area under the Participant Statistical Areas Program (PSAP). In addition to block groups, the program also encompasses the review and update of census tracts, census designated places, and census county divisions. The Census Bureau published a notice, explaining PSAP process and participation, in the Federal Register on November 28, 2017 (82 FR 56208).
I. History of Block Groups
The Census Bureau first delineated block groups as statistical geographic divisions of census tracts for the 1970 Census, comprising contiguous combinations of census blocks for data presentation purposes. At that time, census block groups only existed in urbanized areas in which census blocks were defined. Block groups were defined without regard to political and administrative boundaries, with an average population of 1,000, and to be approximately equal in area.
As use of census block, block group, and census tract data increased among data users, the Census Bureau expanded these programs to cover additional geographic areas while redefining the population threshold criteria to more adequately suit data users' needs. The 1990 Census was the first in which census blocks and block groups were defined throughout the entirety of the United States, Puerto Rico, and the Island Areas. For the 2000 Census, as with census tracts, the Census Bureau increased the number of geographic areas whose boundaries could be used as block group boundaries, and allowed tribal governments of federally recognized American Indian tribes with a reservation and/or off-reservation trust lands to delineate tribal block groups without regard to state and/or county boundaries, provided the tribe had a 1990 Census population of at least 1,000.
For the 2010 Census, the Census Bureau adopted changes to block group criteria that recognized their utility as a framework of small geographic areas and established tribal block groups as a geographic framework for presenting and analyzing statistical and other data for a variety of communities, settlement patterns, and landscapes. The Census Bureau augmented its minimum and maximum population threshold with housing unit thresholds for use in defining block groups for seasonal communities that have no or low population on census day (April 1). In addition, the Census Bureau formalized criteria for block groups defined for employment centers, airports, parks, large water bodies, and other special land uses that had been permitted in previous decades, but never specified within the criteria. The Census Bureau also established tribal block groups as a geographic framework defined within federally recognized American Indian reservations and off-reservation trust lands that is fully separate from the standard block groups defined within counties.
II. Summary of Comments Received in Response to the Proposed Criteria
The Federal Register notice published on February 15, 2018 (83 FR 6937) requested comment on the proposed block group criteria for the 2020 Census. The proposed criteria were unchanged from the final criteria adopted for the 2010 Census.
The Census Bureau received comments from 16 individuals on one or more topics related to (1) use of non-visible political boundaries when defining block groups, (2) use of employment data to define block groups Start Printed Page 56294encompassing areas with substantial amounts of commercial, industrial, or other non-residential activity for the purpose of transportation planning, and (3) defining block groups to align with former census tract boundaries when census tracts are merged. Commenters represented state and local government agencies, regional planning organizations and councils of governments, state data centers, and non-governmental organizations. Comments received by the Census Bureau are summarized below, as well as the Census Bureau's response to these comments.
1. Using Non-Visible Minor Civil Division Boundaries in Michigan as Block Group Boundaries
The Census Bureau received three comments from individuals in Michigan noting that all minor civil division (MCD) boundaries in Michigan should be permitted to be block group boundaries for the 2020 Census as was the case in the past. The commenters correctly noted that in Table 1, Acceptable Minor Civil Division and Incorporated Place Boundaries, the proposed criteria were in error with regard to Michigan. The Census Bureau has corrected the table in the final criteria.
2. Defining Block Groups on the Basis of Employment and Jobs
The Census Bureau received 14 comments related to defining block groups encompassing areas with concentrations of employment and jobs or other types of non-residential uses to improve the utility of block groups for transportation and journey-to-work analysis and planning. Eleven commenters suggested adoption of a minimum threshold of 600 workers/jobs (and no maximum or optimum thresholds) to be applied as an alternative to the existing minimum population or housing unit threshold or in combination with population or housing unit thresholds. One commenter supported the use of worker/job counts when defining block groups, but did not specify a minimum threshold. Two commenters expressed support for modifying criteria for special use block groups primarily to improve identification of block groups encompassing areas with concentrations of employment. One of these commenters noted that applying employment thresholds was not necessary as the sample design for the American Community Survey (which is the source for much of the demographic data used in journey-to-work analysis) focused on residential population concentrations and not employment concentrations. Changes to the special use block group criteria could achieve the result desired by commenters proposing employment thresholds and could also provide greater flexibility when defining block groups.
Based on consideration of the comments received on this topic and further discussion with stakeholders in the transportation community, the Census Bureau will change its criteria for defining special use block groups to no longer specify minimum land area requirements. Special use block groups should be comparable in land area size to surrounding block groups so as to assure data reliability and quality when reporting on workplace-related data and to avoid data disclosure issues. The Census Bureau also recommends that, when defining special use block groups encompassing employment centers and areas with concentrations of jobs, PSAP participants should strive for a minimum threshold of 600 workers/jobs.
3. Defining Block Groups To Follow Former Census Tract Boundaries
One commenter proposed that, when census tracts are merged, an effort should be made to align the boundaries for block groups within the new census tract with the boundaries of the former census tracts that were merged. The commenter noted that this would facilitate historical comparisons of data, particularly when chronicling change in the sociodemographic characteristics of neighborhoods, allowing data users to use block group data to bridge back to previous decades' census tracts.
The Census Bureau agrees with the sentiments expressed by this commenter. We also agree with the suggestion to align block group boundaries with the boundaries of former census tracts in those instances in which census tracts have been merged and will update both the final block group and final census tract criteria accordingly.
III. General Principles and Criteria for Block Groups for the 2020 Census
A. General Principles
1. Block groups are statistical geographic subdivisions of a census tract and are the smallest geographic areas for which the Census Bureau provides sample data, primarily from the ACS 5-year period estimates.
2. Block groups form the geographic framework within which census blocks are numbered.
3. In order to ensure a minimal level of reliability in sample data and minimize potential disclosures of sensitive information, a block group should contain either at least 600 people or at least 240 housing units at minimum, and 3,000 people or 1,200 housing units at maximum. The housing unit criterion is used to accommodate areas that are occupied seasonally and may otherwise show a discrepancy between decennial and ACS figures. 
For the ACS, block groups are not designed to be used individually, rather they provide a smaller geographic area than census tracts that allow data users to combine them to create larger geographic areas that may be more meaningful for their specific use.
4. The Census Bureau also recognizes that there are significant geographic areas that are characterized by unique populations (e.g., prisons or universities) or not characterized by residential populations at all (e.g., National Parks or large bodies of water) which local participants may wish to exclude from populated block groups for either analytical or cartographic purposes. These areas may be designated as special use block groups to distinguish them from standard populated block groups. Special land and/or water use block groups are not required, but if delineated they must be designated as a specific type of special use (discussed below), have an official name, ideally have no residential population or housing units or at least meet all minimum population or housing thresholds mention above, and must not create noncontiguous block groups. While there are no longer minimum land area measurement thresholds for special uses block groups in urban or rural areas, such block groups should be comparable in size to surrounding block groups, particularly if defined to encompass employment centers or other areas containing a greater concentration of jobs than residents. The Census Bureau recognizes that some special use areas not intended for residential population, such as parks, may contain some minimal population, such as caretakers or the homeless, but since the primary purpose of block groups is to help provide high-quality statistical data about the population, the participant and the Census Bureau must decide if a special use block group would be useful in such a situation.Start Printed Page 56295
The criteria herein apply to the United States, including federally recognized American Indian reservations (AIRs) and off-reservation trust lands (ORTLs), Puerto Rico, and the Island Areas. 
The Census Bureau may modify and, if necessary, reject any proposals for block groups that do not meet the published criteria. In addition, the Census Bureau reserves the right to modify the boundaries and attributes of block groups as needed to meet the published criteria and/or maintain geographic relationships before or after the final tabulation geography is set for the 2020 Census.
The Census Bureau sets forth the following criteria for use in reviewing, updating, and delineating 2020 Census block groups:
1. Block groups must not cross census tract boundaries.
This criterion takes precedence over all other criteria or requirements. By definition, because census tracts cannot cross county 
and state boundaries, neither can block groups. It is only permissible to define a block group with fewer than 600 people in a county that has a population less than 600, coextensive with a special use census tract, or as a special use block group delineated within a standard census tract.
2. Block groups must cover the entire land and water area of each census tract.
Because census tracts must cover the entire area of a county, by definition, block groups also must cover the entire area of each census tract within each county.
3. A block group must comprise a reasonably compact and contiguous land area.
Noncontiguous boundaries are permitted only where a contiguous area or inaccessible area would not meet population or housing unit count requirements for a separate block group, in which case the noncontiguous or inaccessible area must be combined within an adjacent or proximate block group. For example, an island that does not meet the minimum population threshold for recognition as a separate block group should be combined with other proximate land to form a single block group. Each case will be reviewed and accepted at the Census Bureau's discretion.
4. Block group boundaries should follow visible and identifiable features.
To make the location of block group boundaries less ambiguous, wherever possible, block group boundaries should follow significant, visible, easily identifiable features. The use of visible features facilitates the location and identification of block group boundaries in the field, both on the ground and in imagery. The selection of permanent physical features also increases the stability of the boundaries over time, as the locations of many visible features in the landscape tend to change infrequently. If block group boundaries are changed, they should not be moved from a more significant feature (e.g., a highway or a major river) to a less significant feature (e.g., a neighborhood road or a small tributary stream). The Census Bureau also requires the use of state and county boundaries in all states to be used as census tract and block group boundaries. The Census Bureau also permits the use of incorporated place and minor civil division (MCD) boundaries in states where those boundaries tend to remain unchanged over time (see Table 1).
The following features are preferred as block group boundaries for the 2020 Census:
a. State, county, and census tract boundaries must always be block group boundaries. This criterion takes precedence over all other boundary criteria or requirements.
b. AIR and ORTL boundaries.
c. Visible, perennial, stable, relatively permanent natural and constructed features, such as roads, shorelines, rivers, perennial streams and canals, railroad tracks, or above-ground high-tension power lines.
d. Boundaries of legal and administrative entities in selected states. Table 1 identifies by state which MCD and incorporated place boundaries may be used as block group boundaries.
e. Additionally, the following legally defined, administrative boundaries are permitted as block group boundaries:
i. Barrio, barrio-pueblo, and subbarrio boundaries in Puerto Rico;
ii. Census subdistrict and estate boundaries in the U.S. Virgin Islands;
iii. County and island boundaries (both MCD equivalents) in American Samoa;
iv. Election district boundaries in Guam;
v. Municipal district boundaries in the Commonwealth of the Northern Mariana Islands; and
vi. Alaska Native Regional corporation boundaries in Alaska, at the discretion of the Census Bureau, insofar as such boundaries are unambiguous for allocating living quarters as part of 2020 Census activities.
f. The boundaries of large parks, forests, airports, penitentiaries/prisons, and/or military installations, provided the boundaries are clearly marked or easily recognized in the field in imagery and on the ground.
g. When acceptable visible and governmental boundary features are not available for use as block group boundaries, the Census Bureau may, at its discretion, approve other nonstandard visible features, such as major ridgelines, above-ground pipelines, intermittent streams, or fence lines. The Census Bureau may also accept, on a case-by-case basis, relatively short stretches of boundaries of selected nonstandard and potentially nonvisible features, such as cadastral and parcel boundaries or the straight-line extensions or other lines-of-sight between acceptable visible features.Start Printed Page 56296
Table 1—Acceptable Minor Civil Division (MCD) and Incorporated Place Boundaries
|State||All MCD boundaries||Boundaries of MCDs not coincident with
the boundaries of incorporated places that themselves are MCDs||All incorporated
boundaries||Only conjoint incorporated place boundaries|
|a Townships only.|
|b Governmental townships only.|
5. Population, Housing Unit, and Area Measurement Thresholds
The following are the population, housing unit, and area measurement threshold criteria for block groups (as summarized in Table 2). The same population and housing unit thresholds apply to all types of non-special use block groups, including those delineated for AIRs and ORTLs, the Island Areas, and encompassing group quarters, military installations, and institutions.Start Printed Page 56297
Table 2—Block Group Thresholds
|Block group type||Threshold types||Minimum||Maximum|
|Standard & tribal block groups||Population thresholds||600||3,000|
| ||Housing unit thresholds||240||1,200|
|Special use block groups||Area measurement||At least comparable in land area size to surrounding block groups||At least comparable in land area size to surrounding block groups.|
| ||Population thresholds||None (or very little), or must be within the standard block group thresholds.|
a. 2010 Census population counts should be used in census block group review in most cases. Housing unit counts should be used for block groups in seasonal communities that have little or no population on Census Day (April 1). Locally produced population and housing unit estimates can be used when reviewing and updating block groups, especially in areas that have experienced considerable growth since the 2010 Census.
b. The housing unit thresholds are based on a national average of 2.5 people per household. The Census Bureau recognizes that there are regional variations to this average, and will take this into consideration when reviewing all census block group proposals.
c. For the 2020 Census, the Census Bureau will allow the delineation of special use census tracts, and special use block groups will be created coextensive with these special use census tracts, but they are not required. A special use census tract, and hence a special use block group, must be designated as a specific use type (e.g., state park), must have an official name (e.g., Jay Cooke State Park), have no (or very little) residential population or meet population or housing unit thresholds, and must not create a noncontiguous census tract/block group. In some instances, multiple areas can be combined to form a single special land use census tract/block group if the land management characteristics are similar, such as a special land use census tract/block group comprising an area with a concentration of employment or adjacent federal and state parks. Any resulting special use census tract/block group should be at least as large in area as the surrounding adjacent standard, populated census tracts/block groups.
6. Identification of Block Groups
a. A block group encompasses a cluster of census blocks. Each standard block group is identified using a single-digit number that will correspond to the first digit in the number of each census block encompassed by the block group. For example, block group 3 includes all census blocks numbered in the 3000 range within a single census tract.
b. The range of acceptable standard block group numbers is 1 through 9.
c. Block group numbers must be unique within a census tract.
7. Block Group Types
Table 3 provides a summary of the types of block groups (with their respective population, housing unit, and area measurement thresholds) that the Census Bureau will use for the 2020 Census.
Table 3—Summary of Block Group Types
|Block group types||Distinction from standard block groups||Population thresholds||Housing unit thresholds||Area measurement thresholds|
|Standard block groups||Min: 600, Max: 3,000||Min: 240, Max: 1,200||None.|
|Tribal block groups||Tribal block groups are conceptually similar and equivalent to census block groups defined within the standard state-county-tract-block group geographic hierarchy used for tabulating and publishing statistical data||Min: 600, Max: 3,000||Min: 240, Max: 1,200||None.|
|Special use block groups||A block group, usually coextensive with a special census tract, encompassing an employment center, large airport, public park, public forest, or large water body with no (or very little) population or housing units||None (or very little) or within the standard block group thresholds||None (or very little) or within the standard block group thresholds||At least comparable in size to surrounding standard block groups.|
C. Tribal Block Groups
Tribal block groups are statistical geographic entities defined by the Census Bureau in cooperation with tribal officials to provide meaningful, relevant, and reliable data for small geographic areas within the boundaries of federally recognized AIRs and/or ORTLs. As such, they recognize the unique statistical data needs of federally recognized American Indian tribes. The delineation of tribal block groups allows for an unambiguous presentation of statistical data specific to the federally recognized AIR and/or ORTL without the imposition of state or county boundaries, which might artificially separate American Indian populations located within a single AIR and/or ORTL. To this end, the American Indian tribal participant may define tribal block groups that cross county or state boundaries, or both. For federally recognized American Indian tribes with AIRs and/or ORTLs that have fewer than 1,200 residents, the Census Bureau will define one tribal census tract and one tribal block group coextensive with the AIR and/or ORTL. Tribal block groups must be delineated to meet all other census block group criteria, and must be identified uniquely so as to clearly distinguish them from county-based block groups. The Census Bureau will address the type of identifiers required for tribal block groups in more detail in a separate Federal Register notice pertaining to all American Indian areas, including statistical areas defined Start Printed Page 56298through PSAP. Tribal block group boundaries will be held as census block boundaries. Census blocks, however, will be numbered uniquely within county-based block groups, and thus there will not be a direct relationship between a tribal block group identifier and the census block numbers. Tribal block groups are conceptually similar and equivalent to census block groups defined within the standard state-county-tract-block group geographic hierarchy used for tabulating and publishing statistical data.
In order to provide meaningful statistical geographic areas within the AIR and/or ORTL, as well as make meaningful and reliable data available for these areas and their populations, tribal block group geography is maintained separately from standard, county-based block groups. This change was first introduced for the 2010 Census, creating standard block groups nationwide and maintaining tribal block groups as a completely separate set of geography from standard block groups for both geographic and data presentation purposes, and eliminates, in part, the reliability and availability data issues for the tribal block groups and the derived standard block groups that were present in Census 2000.
As with standard block groups submitted through this program, the tribal block groups are submitted to the Census Bureau, and are subject to review to ensure compliance with the published criteria. Detailed criteria pertaining to tribal block groups will be published in a separate Federal Register notice pertaining to all American Indian areas, including statistical areas defined through PSAP.
IV. Definitions of Key Terms
Alaska Native Regional Corporation (ANRC)—A corporate geographic area established under the Alaska Native Claims Settlement Act (Pub. L. 92-203, 85 Stat. 688 (1971)) to conduct both the business and nonprofit affairs of Alaska Natives. Twelve ANRCs cover the entire state of Alaska except for the Annette Island Reserve.
American Indian off-reservation trust land (ORTL)—An area of land located outside the boundaries of an AIR, whose boundaries are established by deed, and which are held in trust by the U.S. federal government for a federally recognized American Indian tribe or members of that tribe.
American Indian reservation (AIR)—An area of land with boundaries established by final treaty, statute, executive order, and/or court order and over which a federally recognized American Indian tribal government has governmental authority. Along with “reservation”, designations such as colonies, communities, pueblos, rancherias, and reserves apply to AIRs.
Conjoint—A description of a boundary line shared by two adjacent geographic entities.
Contiguous—A description of areas sharing common boundary lines, more than a single point, such that the areas, when combined, form a single piece of territory. Noncontiguous areas form disjoint pieces.
Group quarters—A location where people live or stay in a group living arrangement that is owned or managed by an entity or organization providing housing and/or services for the residents. This is not a typical household-type living arrangement. These services may include custodial or medical care as well as other types of assistance, and residency is commonly restricted to those receiving these services. People living in group quarters are usually not related to each other. Group quarters include such places as college residence halls, residential treatment centers, skilled nursing facilities, group homes, military barracks, correctional facilities, and workers' dormitories.
Incorporated place—A type of governmental unit, incorporated under state law as a city, town (except in New England, New York, and Wisconsin), borough (except in Alaska and New York), or village, generally to provide governmental services for a concentration of people within legally prescribed boundaries.
Minor civil division (MCD)—The primary governmental or administrative division of a county in 28 states and the Island Areas having legal boundaries, names, and descriptions. The MCDs represent many different types of legal entities with a wide variety of characteristics, powers, and functions depending on the state and type of MCD. In some states, some or all of the incorporated places also constitute MCDs.
Nonvisible feature—A map feature that is not visible on the ground and in imagery such as a city or county boundary through space, a property line, or line-of-sight extension of a road.
Retracting—Substantially changing the boundaries of a census tract so that comparability over time is not maintained.
Special use census tract/block group—Type of census tract or block group that must be designated as a specific use type (e.g., state park or large lake) and have an official name (e.g., Jay Cooke State Park or Lake Minnetonka), should have no (or very little) population or housing units, and must not create a noncontiguous census tract/block group. If delineated in a densely populated, urban area, a special use census tract/block group must have an area of at least one square mile. If delineated completely outside an urban area, a special use census tract/block group must have an area of at least 10 square miles.
Statistical geographic entity—A geographic entity that is specially defined and delineated, such as block group, CDP, or census tract, so that the Census Bureau may tabulate data for it. Designation as a statistical entity neither conveys nor confers legal ownership, entitlement, or jurisdictional authority.
Visible feature—A map feature that can be seen on the ground and in imagery, such as a road, railroad track, major above-ground transmission line or pipeline, river, stream, shoreline, fence, sharply defined mountain ridge, or cliff. A nonstandard visible feature is a feature that may not be clearly defined on the ground (such as a ridge), may be seasonal (such as an intermittent stream), or may be relatively impermanent (such as a fence). The Census Bureau generally requests verification that nonstandard features used as boundaries for the PSAP geographic areas pose no problem in their location during field work.
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Dated: November 1, 2018.
Ron S. Jarmin,
Deputy Director, Performing the Non-Exclusive Functions and Duties of the Director, Bureau of the Census.
[FR Doc. 2018-24570 Filed 11-9-18; 8:45 am]
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