Census Data mapping with the MIT Geodata Repository

*** Download the tool and install it ***

Currently Available Data
How to use the Census Data tool and understand the column names
About the US Census Summary Files

• Summary File 1 (SF 1) – 100% data
• Summary File 3 (SF 3) – sample data

The STFID column as a unique record identifier
Acknowledgements

About

A diverse number of subject areas at MIT use US demographic data in their teaching and research. The US Decennial Census is the primary source for demographic data due to its wide range of questions and consistent collection covering the entire US since 1790. This Census tool makes it easy for the MIT community to easily map Census data from any MIT networked machine running ArcGIS.

Currently Available Data:

Summary File 1, for the state of Massachusetts, New York, and Louisiana at the census tract, block group, block, and zip code tabulation area (ZCTA) (ZCTAs are similar to zip codes) level.

Summary File 3 for the state of Massachusetts, New York, and Louisiana at the census tract, block group, and zip code tabulation area (ZCTA) (ZCTAs are similar to zip codes) level. (The Census Bureau does not release block level data for summary file 3).

For more information about US Census data please visit the MIT Libraries Census guide.

If you would like to request additional areas of the US to be loaded please email gishelp(at)mit.edu. Please note that Census data, while it is rich in information, is large in size, and resources are limited. If you would be willing to be an advocate for increasing available server space for this project please note this with your request.

How to use the Census Data Tool

The census tool is accessible through the MIT Geodata Repository Search Tool. Open ArcMap and select the "Census Data " button in the MIT Geodata Repository search tool, then use your regular MIT Geodata Repository account login and password.

Step 1: Choose the state and summary file of interest.

NOTE: The step numbers refer to the numbers on the diagram below. Use this as a guide throughout the rest of the steps.

Step 2: Select the geographic component

Select one of the "Geographic components" (tract, block group, block, or ZCTA if in SF1 (blocks are not available for SF3)

Note: the smaller the geographic boundary, the larger the file size. Blocks are the smallest Census geography available. It will take noticeably larger to generate a block level file than the other boundary types. It is possible to create a block level file for a whole state, but it will be very large in size and take quite a while to write. Example file sizes for total population for Suffolk County, MA at different geography levels:

tract: 251 KB
block group: 444 KB
block: 3 MB

Step 3: Select the County of interest, or all counties for the state.

Step 4: Subject Components (optional)

By default, all Population and Housing Subject Components are checked, which makes all 286 tables for Summary File 1 display in the Tables (matrices) area below. You can choose to decrease the number of tables listing by unchecking any of the boxes.

Step 5: Select the fields of interest

Click one of the options in the Tables (matrices) area. The fields included in that table will be listed in the Fields area below. Select the field you are interested in by clicking on it. More information about that field can be viewed in the Field Information area (upper right).

Step 6: Add the fields to the output list

Once you have selected the desired field click on the “Add to the Output List” button. When you select the output field, the details of the field are shown in the field information box (upper right). The number of fields that can be added to the output list is only limited by the amount of memory available and ArcMap’s capabilities. You can remove a field from the list by clicking on it in the Output Fields area then clicking the “Remove from the Output List” button. If you change the geographic component, any fields which are not available at that geographic level will be highlighted in red and will not be added to the output shapefile.

Step 7: Specify the path and name of your shapefile

You can either write the output shapefile name and location or open the file menu dialog to locate the file. If you choose to open the dialog to locate the file, after you name it and click Save you must click on the Census box at the bottom of the desktop along the Start menu in order to bring up the Census dialog again and complete Step 9.

Step 8: Create the map.

Click the “Run” button. The selected fields will be joined with the TIGER file of the chosen geographic component to create a new shapefile. The new shapefile will be displayed in ArcMap.

A report containing the detailed field information you selected, including the column code and the descriptive text name, will be generated in dbf format and saved to the same folder as the shapefile and other associated files as filename_tbl.dbf. The column names are based on Census Bureau table names. Example: Total Population = P001001. To see the dbf report file click the "Source" tab in ArcMap (as noted with the arrow in the image below), then right click the table name, and select "open".

Now that you have the file in a GIS system it is easy to symbolize things like population distributions, do spatial analysis with other data of interest, and create maps.

About the US Census Summary Files

Summary File 1 (SF 1) – 100% data

Census 2000, Summary File 1 is a set of information collected from all people and housing units (100 percent population and housing characteristics). Population items include sex, age, race, Hispanic or Latino, household relationship and group quarters. Housing items include occupancy status, vacancy status, and tenure (owner occupied or renter occupied). Selected aggregates and medians also are provided.

There are 286 population and housing tables containing 8,113 fields. These tables provide in-depth figures by race and Hispanic origin; some tables are repeated for each of nine race/Latino groups. Table 1 shows the distribution of the tables (matrices) in Summary file 1.

Table 1. Distribution of the tables (matrices) in Summary File 1.

A complete list of tables and field descriptions is available in the Census 2000 Summary File 1 Technical Documentation at the Census Bureau website: http://www.census.gov/prod/cen2000/doc/sf1.pdf

Summary File 3 (SF 3) – sample data

This file presents data on population and housing from the long form questionnaire, which is collected from a sample of the US population. It includes data on topics such as: income, education, ancestry and selected characteristics for a limited number of race and Hispanic or Latino categories.

As in earlier censuses, the responses from the sample of households reporting on long forms must be weighted to reflect the entire population. Specifically, each responding household represents, on average, six or seven other households who reported using short forms.

The differences between the long form estimates in SF 3 and values in SF 1 or SF 2 are particularly noticeable for the smallest places, tracts, and block groups. The long form estimates of total population and total housing units in SF 3 will, however, match the SF 1 and SF 2 counts for larger geographic areas such as counties and states, and will be essentially the same for medium and large cities.

http://www.census.gov/Press-Release/www/2002/sf3compnote.html

Technical documentation about Summary File 3 can be found at:
http://www.census.gov/prod/cen2000/doc/sf3.pdf

The STFID column as a unique record identifier

The STFID column is made up of a combination of FIPS codes for the geographic area chosen. Each state has a unique 2 digit code, each county has a unique 3 digit code, each tract has 6 digits, each blockgroup has 1 digit and each block has 4 digits. The smaller the geographic component chosen the more longer the STFID column. For more information about FIPS codes visit: http://www.census.gov/geo/www/fips/fips.html.

Acknowledgements:

The Census tool was conceived by German Diaz in the Rice University GIS/Data Center. The original tool was developed by German Diaz and Lisa Sweeney for Harris County, Texas using MS Access and Visual Basic.

The Census tool was later adapted to the MIT Geodata Repository's Oracle/Arc SDE system, so it could be made available via the MIT network, and so it could handle larger amounts of data. This adaptation was made possible through the work of Daniel Sheehan and Xiongjiu Liao.