Obtaining Data

Examples

1. Contemporary Census Data (i.e., 1990-present)
2. Historical Census Data
3. DEM, EPA, etc.

Contemporary Census Data

Instructions: Learn a bit about the surveys available and then about the items/tables they contain.

Decennial Census
American Community Survey

Quick Example

Go to the ACS page on American Factfinder.

Stop, Look, and Answer: When was the data posted?

Click on "2012 ACS 1-year estimates are available in American FactFinder."

Topic > People > Income & Earnings > Income/Earnings (Individuals)

Under Geographies select All US Counties.

In the table selection choose DP03 SELECTED ECONOMIC CHARACTERISTICS. Click on the link and examine the metadata and description.

Stop, Look, and Answer: About what percentage of children did not have health insurance in 2012?

Next we'll download some of the data, but first we'll select just some of the variables to keep things simpler. Click on "Modify Table" …

… and then select just one group of variables ….

Census Data

1. Go to census.gov and under the data tab select American Factfinder
   • Decennial Census more » | get data »
   • Geographies > Census Tract > California > Alameda County > All census tracts
   • Page 2 and back to page 1.

Stop and Think Study the numbers in this summary table. Think about how many different levels of aggregation are presented.

Fill in the table below

Alameda County 2010
Category	Population	Percentage
One Race
Two Races
Three or More Races

+ Show answer

Alameda County 2010
Category	Population	Percentage
One Race	1,419,274	94.0
Two Races	81,914	5.4
Three or More Races	9,083	0.6

How many two-race combinations are reported for Alameda County in 2010?

+ Show answer

14

Download the file and unzip it. First things first, read the read.me file

+READ.ME

This zip file contains a number of documents containing materials related to the table which you have downloaded. These include:

1. aff_download_readme.txt (this file)
2. <table_id>.csv (data file)
3. <table_id>_ann.csv (annotation file, if applicable)
4. <table_id>.txt (notes file)
5. <table_id>_metadata.csv (metadata file)

Naming convention:

The table file name is based on the Table Id.
For Geographic Comparison Tables (GCT) and Geographic Ranking Tables (GRT), the table file name is based on Table ID and Stub.

Document descriptions:

Data file:
file name: <table_id>.csv
Includes the tabular data for the table.

Annotation file:
file name: <table_id>_ann.csv
This file contains cell annotations, which could be simple jam values, flag symbols, or codes of more complex cell annotations that replace the values in the data file. This file has a parallel structure to the data file, but it includes only those lines that correspond to the lines from the data file that have annotations. If there are no lines to be included in the annotation file, then the whole annotation file is omitted. A cell annotation starts with '$' or 'ECONF$', and the string that follows the '$' char is the jamming string or flag symbol. For example, '$1000+' is a simple cell annotation that would replace the content of the cell with the string '1000+'. A cell annotation that does not start with '$', such as 'ECONF$', is a code that is described in the notes file (see below).

Notes file:
file name: <table_id>.txt
This file contains the head notes, footnotes and the description of the cell annotations occurring in the data file (simple jamming cell annotations are excluded).

Metadata file:
file name: <table_id>_metadata.csv
This file contains the header information (transposed), without the data associated with the table.

Historical Census Data

The 1940 census is online (the actual tabulation forms used by enumerators). We'll locate the sheets for Mills and surrounding areas and create a crowd-sourced data file based on them.

Start with search option one ("Do you know the location where the person lived?") and look for California/Alameda/Oakland. When the page comes up, click on the map link. Note that Oakland comprises enumeration districts ED 61-1 to ED 61-296.

But there's an easier way to zoom in on Mills. We'll just enter it as the street name

Toxic Release Data

Go to TRI Search Page. Look for releases of "methanol" in Alameda County.
Download the csv file.
Import into QGIS. Map the points.

OR

Go to EPA's Cleanup Sites Search Engine. Look for brownfields in Alameda County. Download the csv. Use Batch Geocode if no long/lat, save as CSV, import and map.

Elevation Maps

Read about DEMs.
Check out the The National Map Viewer and Download Platform
Alameda County elevation data here

File name	File type	Size
counties.zip	Zip archive data	897.49 kB	Info
HeinzSchool_ImportingSpatialAttributeData.pptx	No description	5.41 MB	Info

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