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Census Geography

Block group (BG)

A combination of census blocks that is a subdivision of a census tract or BNA. A BG consists of all blocks whose numbers begin with the same digit in a given census tract or BNA; for example, BG 3 within a census tract or BNA includes all blocks numbered between 301 and 399.

Format Viewing Software Coverage Census Location Call #
TIGER CD-ROM Landview U.S. 1990 Rm. 412  
Wessex CD-ROM ArcView U.S. 1990 Rm. 412  
paper   Illinois 1990 Rm. 418 see Census Tracts and Block Groups Map

Block numbering area (BNA)

An area delineated by State officials or (lacking State participation) by the Census Bureau, following Census Bureau guidelines, for the purpose of grouping and numbering decennial census blocks in counties or statistically equivalent entities in which census tracts have not been established. A BNA is equivalent to a census tract in the Census Bureau’s geographic hierarchy.

Format Viewing Software Coverage Census Location Call #
paper   Illinois 1990 Rm. 408 see Census Tracts and Block Numbering Area Outline Map

Census block

The smallest entity for which the Census Bureau collects and tabulates decennial census information; bounded on all sides by visible and nonvisible features shown on Census Bureau maps.

Format Viewing Software Coverage Census Location Call #
IL GIS CD-ROM ArcView Illinois 1990 Rm. 418  

Census tract

A small, relatively permanent statistical subdivision of a county in a metropolitan area (MA) or a selected nonmetropolitan county, delineated by a local committee of census data users for the purpose of presenting decennial census data. Census tract boundaries normally follow visible features, but may follow governmental unit boundaries and other nonvisible features in some instances; they always nest within counties.

Format Viewing Software Coverage Census Location Call #
TIGER CD-ROM Landview U.S. 1990 Rm. 412  
Wessex CD-ROM ArcView U.S. 1990 Rm. 412  
paper   Illinois 1990 Rm. 418, Rm. 408 also see Census Tracts and Block Groups Map and Census Tracts and Block Numbering Area Outline Map
paper   Champaign-Urbana 1990 Rm. 418 G4104.C5 E25 1990 .C5
paper   Champaign-Urbana-Rantoul MSA 1970, 1980 Rm. 418 G4103s.C449 E2 1972 .U5

G4103.C4 E25 1980 .U5

paper   Chicago MSA 1980 Rm. 418 G4104.C6 E25 1980 .U5
paper   Chicago 1960, 1970 Rm. 418 G4104.C56 E25 1960 .C4

G4104.C6 E25 1970 .C6
paper   Kankakee MSA 1980 Rm. 418 G4104.K2 E25 1980 .U5
paper   Peoria MSA 1980 Rm. 418 G4104.P4 E25 1980 .U5
paper   Rockford MSA 1980 Rm. 418 G4104.R7 E25 1980 .U5
paper   Springfield MSA 1980 Rm. 418 G4104.S5 E25 1980 .U5

Census Tracts and Block Groups Map

Format Viewing Software Coverage Census Location Call #
paper   Champaign-Urbana 1990 Rm. 418 G4104.C5 E25 1990 .C5
paper   Rantoul 1990 Rm. 418 G4104.R2 E25 1990 .C5

Census Tract/Block Numbering Area Outline Map

A map (or set of maps) depicting the boundaries and numbers of census tracts/BNAs in a county or equivalent entity. The map also displays features and feature names underlying the boundaries, and the boundaries and names of counties, AIANAs, county subdivisions, and places (but not the street pattern within census tracts/BNAs).

Format Viewing Software Coverage Census Location Call #
paper   Bloomington-Normal MA 1990 Rm. 408 G4103.M59 E25 1990 .C4
paper   Champaign-Urbana-Rantoul MA 1990 Rm. 408 G4103.C4 E25 1990 .U5
paper   Chicago-Gary-Lake MA (Aurora-Elgin PMSA) 1990 Rm. 408 G4104.C6 E25 1990 .C4
paper   Chicago-Gary-Lake MA (Chicago PMSA) 1990 Rm. 408 G4104.C6 E25 1990 .C43
paper   Chicago-Gary-Lake MA (Joliet PMSA) 1990 Rm. 408 G4104.C6 E25 1990 .C41
paper   Chicago-Gary-Lake MA (Lake PMSA) 1990 Rm. 408 G4104.C6 E25 1990 .C42
paper   Decatur MA 1990 Rm. 408 G4104.D3 E25 1990 .C4
paper   Kankakee MA 1990 Rm. 408 G4103.K3 E25 1990 .C4
paper   Peoria MA 1990 Rm. 408 G4104.P4 E25 1990 .C4
paper   Rockford MA 1990 Rm. 408 G4104.R7 E25 1990 .C4
paper   Springfield MA 1990 Rm. 408 G4104.S5 E25 1990 .C4
paper   St. Louis, MO-IL MA 1990 Rm. 408 G4164.S4 E25 1990 .C4
paper   IL counties outside of MAs: 1990 Rm. 408  
    Adams Co. 1990 Rm. 408 G4103.A2 E25 1990.C4
    Alexander Co. 1990 Rm. 408 G4103.A5 E25 1990.C4
    Bond Co. 1990 Rm. 408 G4103.B5 E25 1990.C4
    Brown Co. 1990 Rm. 408 G4103.B7 E25 1990.C4
    Bureau Co. 1990 Rm. 408 G4103.B8 E25 1990.C4
    Calhoun Co. 1990 Rm. 408 G4103.C2 E25 1990.C4
    Carroll Co. 1990 Rm. 408 G4103.C25 E25 1990.C4
    Cass Co. 1990 Rm. 408 G4103.C3 E25 1990.C4
    Christian Co. 1990 Rm. 408 G4103.C45 E25 1990.C4
    Clark Co. 1990 Rm. 408 G4103.C5 E25 1990.C4
    Clay Co. 1990 Rm. 408 G4103.C55 E25 1990.C4
    Coles Co. 1990 Rm. 408 G4103.C6 E25 1990.C4
    Crawford Co. 1990 Rm. 408 G4103.C8 E25 1990.C4
    Cumberland Co. 1990 Rm. 408 G4103.C9 E25 1990.C4
    DeKalb Co. 1990 Rm. 408 G4103.D4 E25 1990.C4
    DeWitt Co. 1990 Rm. 408 G4103.D5 E25 1990.C4
    Douglas Co. 1990 Rm. 408 G4103.D6 E25 1990.C4
    Edgar Co. 1990 Rm. 408 G4103.E2 E25 1990.C4
    Edwards Co. 1990 Rm. 408 G4103.E3 E25 1990.C4
    Effingham Co. 1990 Rm. 408 G4103.E4 E25 1990.C4
    Fayette Co. 1990 Rm. 408 G4103.F3 E25 1990.C4
    Ford Co. 1990 Rm. 408 G4103.F6 E25 1990.C4
    Franklin Co. 1990 Rm. 408 G4103.F7 E25 1990.C4
    Fulton Co. 1990 Rm. 408 G4103.F8 E25 1990.C4
    Gallatin Co. 1990 Rm. 408 G4103.G3 E25 1990.C4
    Greene Co. 1990 Rm. 408 G4103.G7 E25 1990.C4
    Hamilton Co. 1990 Rm. 408 G4103.H2 E25 1990.C4
    Hancock Co. 1990 Rm. 408 G4103.H3 E25 1990.C4
    Hardin Co. 1990 Rm. 408 G4103.H4 E25 1990.C4
    Henderson Co. 1990 Rm. 408 G4103.H5 E25 1990.C4
    Iroquois Co. 1990 Rm. 408 G4103.I6 E25 1990.C4
    Jackson Co. 1990 Rm. 408 G4103.J2 E25 1990.C4
    Jasper Co. 1990 Rm. 408 G4103.J3 E25 1990.C4
    Jefferson Co. 1990 Rm. 408 G4103.J4 E25 1990.C4
    JoDaviess Co. 1990 Rm. 408 G4103.J6 E25 1990.C4
    Johnson Co. 1990 Rm. 408 G4103.J7 E25 1990.C4
    Knox Co. 1990 Rm. 408 G4103.K6 E25 1990.C4
    LaSalle Co. 1990 Rm. 408 G4103.L15 E25 1990.C4
    Lawrence Co. 1990 Rm. 408 G4103.L4 E25 1990.C4
    Lee Co. 1990 Rm. 408 G4103.L5 E25 1990.C4
    Livingston Co. 1990 Rm. 408 G4103.L6 E25 1990.C4
    Logan Co. 1990 Rm. 408 G4103.L7 E25 1990.C4
    McDonough Co. 1990 Rm. 408 G4103.M57 E25 1990.C4
    Macoupin Co. 1990 Rm. 408 G4103.M35 E25 1990.C4
    Marion Co. 1990 Rm. 408 G4103.M43 E25 1990.C4
    Marshall Co. 1990 Rm. 408 G4103.M46 E25 1990.C4
    Mason Co. 1990 Rm. 408 G4103.M5 E25 1990.C4
    Massac Co. 1990 Rm. 408 G4103.M55 E25 1990.C4
    Mercer Co. 1990 Rm. 408 G4103.M65 E25 1990.C4
    Montgomery Co. 1990 Rm. 408 G4103.M75 E25 1990.C4
    Morgan Co. 1990 Rm. 408 G4103.M8 E25 1990.C4
    Moultrie Co. 1990 Rm. 408 G4103.M9 E25 1990.C4
    Ogle Co. 1990 Rm. 408 G4103.O3 E25 1990.C4
    Perry Co. 1990 Rm. 408 G4103.P4 E25 1990.C4
    Piatt Co. 1990 Rm. 408 G4103.P5 E25 1990.C4
    Pike Co. 1990 Rm. 408 G4103.P6 E25 1990.C4
    Pope Co. 1990 Rm. 408 G4103.P7 E25 1990.C4
    Pulaski Co. 1990 Rm. 408 G4103.P8 E25 1990.C4
    Putnam Co. 1990 Rm. 408 G4103.P9 E25 1990.C4
    Randolph Co. 1990 Rm. 408 G4103.R3 E25 1990.C4
    Richland Co. 1990 Rm. 408 G4103.R5 E25 1990.C4
    Saline Co. 1990 Rm. 408 G4103.S3 E25 1990.C4
    Schuyler Co. 1990 Rm. 408 G4103.S5 E25 1990.C4
    Scott Co. 1990 Rm. 408 G4103.S6 E25 1990.C4
    Shelby Co. 1990 Rm. 408 G4103.S7 E25 1990.C4
    Stark Co. 1990 Rm. 408 G4103.S8 E25 1990.C4
    Stephenson Co. 1990 Rm. 408 G4103.S9 E25 1990.C4
    Union Co. 1990 Rm. 408 G4103.U5 E25 1990.C4
    Vermilion Co. 1990 Rm. 408 G4103.V4 E25 1990.C4
    Wabash Co. 1990 Rm. 408 G4103.W2 E25 1990.C4
    Warren Co. 1990 Rm. 408 G4103.W3 E25 1990.C4
    Washington Co. 1990 Rm. 408 G4103.W35 E25 1990.C4
    Wayne Co. 1990 Rm. 408 G4103.W4 E25 1990.C4
    White Co. 1990 Rm. 408 G4103.W5 E25 1990.C4
    Whiteside Co. 1990 Rm. 408 G4103.W55 E25 1990.C4
    Williamson Co. 1990 Rm. 408 G4103.W7 E25 1990.C4

Congressional district (CD)

An area established by State officials or the courts for the purpose of electing a person to the U.S. House of Representatives. Within each State, these areas must contain, as nearly as possible, an equal number of inhabitants. The number of CDs in each State may change after each decennial census, and the boundaries may be changed more than once during a decade.

Format Viewing Software Coverage Census Location Call #
Wessex CD-ROM ArcView U.S. 1990 Rm. 412  
IL GIS CD-ROM ArcView Illinois 1990 Rm. 418  

County Block Map

A set of large-scale maps for each county or equivalent entity, displaying boundaries and names/numbers of census blocks, decennial census tabulation entities, and ground features such as roads and streams. These maps are the most detailed and complete set of cartographic information that the Census Bureau provides.

Format Viewing Software Coverage Census Location Call #
paper   Cook County 1990 Rm. 408 G4103.C7 E25 1990 .C41
paper   DuPage County 1990 Rm. 408 G4103.D8 E25 1990 .C41
paper   Lake County 1990 Rm. 408 G4103.L2 E25 1990 .C41

Enumeration district (ED)

A small geographic entity established by the Census Bureau as a basic unit for data collection and tabulation in a decennial or special census before 1990. (For the 1970 and 1980 censuses it was superseded by the BG as the lowest level for which the Census Bureau tabulated sample data in those areas that had block numbers assigned.) An ED usually consisted of the area to be assigned to an individual enumerator for canvassing. All area included in a single ED was in the same governmental unit(s) or statistical area(s). The ED was replaced by the address register area (ARA) for data collection purposes in the 1990 census; it also was totally replaced by the BG as the lowest level of geography for which the Census Bureau tabulated sample data.

Format Viewing Software Coverage Census Location Call #
paper   Chicago 1950 Rm. 418 G4104.C6 E25 1950 .C43

Metropolitan area (MA)

A collective term, established by the Federal OMB and used for the first time in 1990, to refer to metropolitan statistical areas (MSAs), consolidated metropolitan statistical areas (CMSAs), and primary metropolitan statistical areas (PMSAs). In addition, there is an alternative set of areas termed NECMAs.

Metropolitan statistical area (MSA)

A geographic entity, defined by the Federal OMB for use by Federal statistical agencies, based on the concept of a core area with a large population nucleus, plus adjacent communities having a high degree of economic and social integration with that core. Qualification of an MSA requires the presence of a city with 50,000 or more inhabitants, or the presence of a UA and a total population of at least 100,000 (75,000 in New England). The county or counties containing the largest city and surrounding densely settled territory are central counties of the MSA. Additional outlying counties qualify to be included in the MSA by meeting certain other criteria of metropolitan character, such as a specified minimum population density or percentage of the population that is

urban. MSAs in New England are defined in terms of cities and towns, following rules concerning commuting and population density. MSAs were first defined and effective June 30, 1983.

Format Viewing Software Coverage Census Location Call #
ArcUSA CD-ROM ArcView U.S. 1990 Rm. 412  
CTPP CD-ROM TransVU U.S. 1990 Rm. 412  
paper   U.S. MSAs and PMSAs 1990 Rm. 418 G3690 1994 .E2

Minor civil division (MCD)

A type of governmental unit that is the primary legal subdivision of a county in 28 States, created to govern or administer an area rather than a specific population. The several types of MCDs are identified by a variety of terms, such as town, township, and district, and include both functioning and nonfunctioning governmental units. Many MCDs represent local, general-purpose governmental units, which makes them required areas for presentation of decennial census data.

Format Viewing Software Coverage Census Location Call #
Wessex CD-ROM ArcView U.S. 1990 Rm. 412  
CTPP CD-ROM TransVU U.S. 1990 Rm. 412  
IL GIS CD-ROM ArcView Illinois 1990 Rm. 418  

Place

A concentration of population either legally bounded as an incorporated place, or identified by the Census Bureau as a CDP. Incorporated places have political/statistical descriptions of borough (except in Alaska and New York), city, town (except in New England, New York, and Wisconsin), or village.

Format Viewing Software Coverage Census Location Call #
Wessex CD-ROM ArcView U.S. 1990 Rm. 412  
CTPP CD-ROM TransVU U.S. 1990 Rm. 412  
IL GIS CD-ROM ArcView Illinois 1990 Rm. 418  

Primary metropolitan statistical area (PMSA)

A geographic entity defined by the Federal OMB for use by Federal statistical agencies. If an area meets the requirements to qualify as a metropolitan statistical area (MSA) and has a population of one million or more, two or more PMSAs may be defined within it if statistical criteria are met and local opinion is in favor. A PMSA consists of a large urbanized county, or a cluster of such counties (cities and towns in New England) that have substantial commuting interchange. When one or more PMSAs have been recognized, the balance of the original, larger area becomes an additional PMSA; the larger area of which they are components then is designated a consolidated metropolitan statistical area (CMSA). PMSAs were first defined and effective on June 30, 1983.

Format Viewing Software Coverage Census Location Call #
ArcUSA CD-ROM ArcView U.S. 1990 Rm. 412  
CTPP CD-ROM TransVU U.S. 1990 Rm. 412  
paper   U.S. MSAs and PMSAs 1990 Rm. 418 G3690 1994 .E2

Urbanized area (UA)

An area consisting of a central place(s) and adjacent urban fringe that together have a minimum residential population of at least 50,000 people and generally an overall population density of at least 1,000 people per square mile of land area. The Census Bureau uses published criteria to determine the qualification and boundaries of UAs.

Format Viewing Software Coverage Census Location Call #
CTPP CD-ROM TransVU U.S. 1990 Rm. 412  

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Updated: 12.05.2006 jmj