CENSUS 2010: STEPS FOR DETERMINING A PUBLIC LIBRARY DISTRICT’S POPULATION USING CENSUS TRACT AND BLOCK DATA NOTE: Use the methods described below when your district’s boundaries do not follow “standard” geographic boundaries such as municipal (city, town, village), township, county, or school district. If you are unsure about how to proceed or need guidance, then contact: Robert Jones State Data Coordinator Illinois State Library Library Development Group E-mail: [email protected] Phone: 217-785-1168 Fax: 217-782-1877 STEP 1: USE THE ILLINOIS DEPARTMENT OF REVENUE COUNTY TAXING MAPS TO IDENTIFY THE LIBRARY DISTRICT’S LEGAL BOUNDARIES These maps, arranged by county, represent the library district’s taxing boundaries. Use these maps in comparison with the Census maps to determine the library district’s Census Tract and Block numbers. Begin at this URL: http://ediillinois.org/ppa/meta/html/00/00/00/02/92/25.html Scroll down the page and select the appropriate county (repeat as necessary for multiple counties). Select: map showing all Library district boundaries in the county (LIB.pdf) and click on the hypertext LIB.pdf. Identify your district’s taxing boundaries in order to compare those boundaries with the Census tract and block maps. STEP 2: USE THE 2010 CENSUS TRACT AND BLOCK MAPS TO IDENTIFY THE LIBRARY DISTRICT’S LEGAL CENSUS BOUNDARIES 2.1 – DETERMINE TRACT NUMBER(S) FOR THE PUBLIC LIBRARY DISTRICT Compare the library district’s county taxing map with the county Census tract map(s) to determine the library district’s corresponding Census tracts(s), either full or partial coverage. Record the Census tract numbers and indicate full or partial coverage. You will need to document this information in order to later use 1

American FactFinder (New American FactFinder/FactFinder 2) to find the population counts. Begin at this URL: http://www.census.gov/geo/www/maps/pl10_map_suite/tract.html On the page 2010 Census - Census Tract Reference Maps select: Illinois On the page 2010 Census – Census Tract Reference Maps select: the appropriate county The resulting “directory” choices appear: Parent Directory, .pdf, and .txt files If you click on Parent Directory: then a county list will be re-displayed. .pdf files and .txt files will be explained below in “Notes” NOTES: .PDF FILES A.

COUNTIES WITH ONLY 1 MAP SHEET: SUFFIX 001.PDF (Example: DC10CT_C17001_001.pdf) Ninety-four Illinois counties each have a single sheet map, ending with the suffix 001.pdf, that details all the Census tracts for that particular county. When you select this map, you should view and understand the map’s Legend to recognize how to identify: • Census Tract Boundaries • Census Tract Numbers (Red) Compare your district’s taxing boundaries with this Census tract map to determine the Census tract numbers within your library district’s legal service area. Record, for your library district’s taxing boundaries: (1) all the tract numbers and (2) whether you legally service those tracts in whole or in part. If your district geography “matches” whole Census tracts exactly, then proceed to Section 3.1 below (population statistics). If your districts geography includes partial tracts, then you will need to proceed to Section 2.2 below (block maps).

B.

COUNTIES WITH MORE THAN 1 MAP SHEET: SUFFIX 000 (AND CONSECUTIVE NUMBERING).PDF (EXAMPLE: DC10CT_C17031_000.pdf and DC10CT_C17031_001.pdf) Eight Illinois counties have more than 1 map sheet that details the Census tracts for that particular county. 2

The index map for the county is: • identified with a suffix of 000.pdf • used to identify the specific map sheets your will need to determine Census tract numbers • divided into boundaries using blue lines and blue numbers. The blue numbers refer to the specific map sheets (suffixes 001.pdf, et seq.) that will contain the Census tract geography for that area of the county. Use the index map to identify the specific map sheet(s) you will need to use in order to determine your library district’s tract number(s). Go back one screen and click on the specific map sheet number (suffix “number.”pdf)--for example, DC10CT_C17031_005.pdf. When you select this map, you should view and understand the map’s Legend to recognize how to identify: • Census Tract Boundaries • Census Tract Numbers (Red) Compare your district’s taxing boundaries with this Census tract map to determine the Census tract numbers within your library district’s legal service area. Record, for your library district’s taxing boundaries: (1) all the tract numbers and (2) whether you legally service those tracts in whole or in part. If your district geography “matches” whole Census tracts exactly, then proceed to Section 3.1 below (determining population). If your districts geography includes partial tracts, then you will need to proceed to Section 2.2 below (block numbers). NOTES: .TXT FILES Recommendation: Do not use the Census tract .txt files. If you are using the .txt files proceed with caution as noted below! The .txt file can be used to translate 2010 Census tract numbers to map sheet numbers but only if (a) the valid 2010 Census tract numbers are known in advance and (b) your county(ies) have more than one Census tract map. The header key for the .txt file is: TYPE;CODE;NAME;SHEETS. Note that each data element is separated by a semicolon (;). • • •

TYPE = TRACT map (type of map) CODE = FIPS Code for Illinois NAME = The specific tract number 3

•

SHEETS = Refers to the specific tract map sheet

You would then proceed to the map sheets per the Notes “B” section above.

2.2 – DETERMINE BLOCK NUMBER(S) FOR THE PUBLIC LIBRARY DISTRICT Once the library district’s Census tract boundaries have been determined, then the blocks for any “partial” tract(s) coverage needs to be identified. “Partial” simply means that your library district’s legal service area encompasses only “a part of” rather than the whole of a tract(s) which necessitates using the next smaller level of Census data— the Census block(s). To locate Census block data, your search will begin with your library district’s Census tract numbers (as determined using processes in 2.1 above). Use the Census block map .txt files (NOT the Census tract map .txt files) to determine the appropriate block map sheets you will need to view in order to determine the specific Census block numbers for your district’s legal service area. Begin at this URL: http://www.census.gov/geo/www/maps/DC10_GUBlkMap/dc10blk_main.html On the page 2010 Census - Census Block Maps select: Illinois On the page Illinois, 2010 Census – Census Block Maps select: County or County Equivalent On the page Illinois, 2010 Census Block Maps – County select: the appropriate county The resulting “directory” choices appear: Parent Directory, .pdf, and .txt files (For now you should ignore the Parent Directory and the .pdf files.) Select the .txt file. Look at the display and find the .txt suffix. (The .txt file is typically in the middle of the list, preceded by block map sheets in .pdf format and interspersed alphabetically with the block map inset sheets in .pdf format). Example from Adams County: DC10BLK_C17001_BLK2MS.txt. UNDERSTANDING THE .TXT FILE CITATIONS The header key for the .txt file is: TYPE;STATE;COUNTY;TRACT;BLOCK;SHEETS. Note that each data element is separated by a semicolon (;). Examples follow. Example 1: Census Block;17;001;1.00;1000;10 TYPE = CENSUS BLOCK (type of map) STATE = 17 (Illinois) 4

COUNTY = 001 (Adams, each Illinois County has a unique number) TRACT = 1.00 (Tract #) BLOCK = 1000 (Block #) SHEETS = 10 (Map sheet #) Example 2: Census Block;17;001;1.00;1004;9,10 TYPE = CENSUS BLOCK (type of map) STATE = 17 (Illinois) COUNTY = 001 (Adams) TRACT = 1.00 BLOCK = 1004 SHEETS = use map sheet number 9 and 10 Example 3: Census Block;17;001;1.00;1018;J3 TYPE = CENSUS BLOCK (type of map) STATE = 17 (Illinois) COUNTY = 001 (Adams) TRACT = 1.00 BLOCK = 1018 SHEETS = use map sheet number J3 (alpha-numeric maps are inset maps, typically for populated places) Carefully scroll through the entire .txt file list to find your district’s tract number(s) in the tract column (see section, UNDERSTANDING THE .TXT FILE CITATIONS.) Note that the tract number(s) are repeated many times. Why? The blocks, which are the smaller geographic unit, are being tied to a tract or tract(s). This example may make it clearer. Look at Adams County’s .txt file. Tract 1.00 has 174 entries. The blocks run from 1000-1066, 2000-2022, 3000-3032, 4000-4029, 5000-5021. Record the corresponding block map sheet numbers (see section, UNDERSTANDING THE .TXT FILE CITATIONS) that correspond to your district’s tract number(s). Example: Look at Adams County’s .txt file. Tract 1.00 has 174 entries. The blocks run from 1000-1066, 2000-2022, 3000-3032, 4000-4029, 5000-5021. Next record the map sheet numbers that correspond to that tract: 9, 10, J2, J3. Therefore, you will need to look at these .pdf files in the block maps for Adams County: 009.pdf, 010.pdf, J02.pdf, J03.pdf. Reminders/Caution: • In order to make sure you locate all the block map sheets you will need to review, you MUST carefully scroll through all of your identified tracts in order to record the block map sheets you need. 5

Census block numbers repeat within each Census tract, so be extremely careful to ensure that you are working in the correct Census tract number when recording block map sheet numbers. Using Adams County again as the example: Census tract 1.00’s block numbers range is1000-1066, Census tract 2.01’s block numbers range is 1000-1041. Once you have determined all of the map sheets you will need to determine specific blocks in your library district’s legal service area, re-navigate to and click on the county or county equivalent link within the block map page. Select the appropriate map sheets from the displayed list. Example 1: Census Tract 102.00: 17;001;102.00;4000;8 (map sheet 8 is one of several •

map sheets for tract 102.00) In the display list, click on: DC10BLK_C17001_008.pdf (008.pdf is the corresponding map sheet for 17;001;102.00;4000;8 noted above.) Example 2 Census Tract 102.00: 17;001;102.00;4009;I1 (map sheet I1 is one of several

map sheets for tract 102.00) In the display list, click on: DC10BLK_C17001_I01.pdf (I01.pdf is the corresponding inset map sheet for 17;001;102.00;4009;I1) REMINDER When you are viewing the .pdf map sheets in order to determine block numbers, review the map’s Legend to recognize how to identify: • Census Tract Boundaries • Census Tract Numbers (big red) • Census Block Boundaries • Census Block Numbers (smaller red) Again, just like you did with the tracts, compare your library district’s county taxing map with the county Census block map(s) to determine the library district’s corresponding Census block(s), either full or partial coverage. Record the Census block numbers and indicate full or partial coverage. You will need to document this information in order to later use American FactFinder (New American FactFinder/FactFinder 2) to find the population counts. Now that you have determined Census block information, proceed to Section 3.2 (population statistics) below to determine the population for those blocks within the correctly identified tracts. STEP 3: USE THE TRACT NUMBER(S) AND BLOCK NUMBER(S) INFORMATION TO DETERMINE THE POPULATION USING THE NEW AMERICAN FACTFINDER (FACTFINDER 2)

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3.1 - FIND POPULATION STATISTICS FOR CENSUS TRACTS USING THE NEW AMERICAN FACTFINDER/FACTFINDER2 http://factfinder2.census.gov/faces/nav/jsf/pages/index.xhtml Near the top center of screen select: View 2010 Census tables Left side of screen select: Geographies (light blue background) A “pop-up screen” opens with the Header: Select Geographies (white text, gray background) Center of “pop-up screen” on left, under Geography Filter Options (blue header, white text) select: Summary Level Under Geography Filter Options select: 140 – Census Tract Under Geography Filter Options select: Within State Under Within State select: Illinois Select the county from the right hand side of the “pop-up screen” with the header Geography Results (blue header, white text) Click the word “Add” Close the “Select Geographies box” (which is the center screen/gray header, white text) by selecting the “x” in the upper right corner of the pop-up screen Select Table P1 – Race Click View (blue text, top or bottom of screen) Note that the total population for each tract is the top row of the data Scroll through the pages, find the tract numbers and populations appropriate for your district, and document all the information. 3.2 - FIND POPULATION STATISTICS FOR CENSUS BLOCKS USING THE NEW AMERICAN FACTFINDER/FACTFINDER2 http://factfinder2.census.gov/faces/nav/jsf/pages/index.xhtml Near the top center of screen select: View 2010 Census tables Left side of screen select: Geographies (light blue background) A “pop-up screen” opens with the Header: Select Geographies (white text, gray background) Center of “pop-up screen” on left, under Geography Filter Options (blue header, white text) select: Summary Level Under Geography Filter Options select: 100 – Block Under Geography Filter Options select: Within State Under Within State select: Illinois

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Select the county from the right hand side of the “pop-up screen” with the header Geography Results (blue header, white text) Click the word “Add” Close the “Select Geographies box” (which is the center screen/gray header, white text) by selecting the “x” in the upper right corner of the pop-up screen Select Table P1 – Race Click View (blue text, top or bottom of screen) Note that the total population for each block group (and corresponding tract number) is the top row of the data. Scroll through the pages, find the correct tract number first and then the correct block numbers and corresponding populations that are appropriate for your district, and as the final step document all the information. STEP 4: SUBMIT YOUR PUBLIC LIBRARY DISTRICT’S POPULATION DATA VERIFICATION AND CALCULATION TO THE ILLINOIS STATE LIBRARY Send the Illinois State Library the documentation that justifies your library district’s population. Include the documentation of your district’s taxing area by County, Census tract numbers, and Census Block numbers with the corresponding populations for the tracts and/or blocks that were used to calculate your district’s population using the Census 2010 data. This documentation should be submitted to: Illinois State Library Gwendolyn Brooks Building ATTN: 2010 Library District Population Library Development Group 300 South Second Street Springfield, Illinois 62701-1796

Prepared by: Ron Winner and Arlyn Booth Final Version: June 22, 2011

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