GEO 266: Mapping Census Data



Lab 1: Mapping Census Data

Introduction

This lab is intended to be a review of tools and concepts from Introduction to GIS. For those of you who have not taken the course at PCC, this lab will be a refresher crash course and give you an idea of what prior knowledge is expected upon entering the advanced course. It will also introduce you to the new ArcGIS version 10 tools and interface.

In this lab you will review the following:

▪ Download geographic data

▪ Projections

▪ Join tables (.xls files)

▪ Classifying data

▪ Map design & production

▪ What's new in ArcGIS 10

Instructions

Thoroughly read the descriptions provided in the exercise on data files, navigating around the census website and using tools in ArcMap. Complete the following exercises described below on compiling, classifying, and mapping census data in Oregon.

Deliverables

You will turn in answers to questions (in bold) and 4 presentation quality maps. All maps should be inserted in your lab document. Labs should be emailed to me in .pdf format.

PART I: USING ARCMAP IN ARCGIS DESKTOP 10

Log in to your ESRI Global account and go to Training (). Click on Find Training and search for the course, “Using ArcMap in ArcGIS Desktop 10” and click on 'go to course.'

Follow all the steps, including watching the presentation, completing the exercise and take the exam.

1. List three examples of differences between Version 9.3 and 10.

PART II: STEPS FOR CONVERTING DATA FILES

Zip Files

GIS data are available online in a number of different formats. Most datasets will be in some sort of compressed (zipped) format. However, all zip formats are not read by all compression / extraction software. Windows XP will open .zip files. 7-Zip, which is available as a free download, should open all the zip formats you will find for GIS datasets (.zip, .gz, and .tar files).

.E00 File Conversion

As you know, GIS programs work with many different data file types.

On the Census website, you are going to see E00 files (in addition to shapefiles), which are ESRI ArcInfo interchange files (also called Export files). If you download an E00 file and unzip it, you still cannot view it directly in ArcMap: it must be converted into a coverage data file.

Converting an .e00 file:

▪ Open the ArcToolbox window and choose Coverage Tools>Conversion>Import from Interchange File.

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▪ The Input file is the E00 file and the Output Dataset what you want to call the coverage file (make sure there are no spaces in the path to the location of your file)

▪ You can now add the coverage to ArcMap or view in ArcCatalog

PART III: CREATING MAPS WITH CENSUS DATA

Answer the questions in bold.

1. Visit the US Census website (). This is a big confusing place but it has a lot of useful information.

a. Click on the Geography link, then on Maps and Mapping Resources. Take a few minutes to explore the different links on this page. What GIS data types are available to download from the site? What kind of information is available?

b. Click on Boundary Files, and follow the link to 'Download Boundary Files' on the left. Follow the links to download the counties (County and County Equivalent Areas – 2000). This will lead you to a page that has options for downloading each individual state, or all 50 states (at the bottom of the list) in both .e00 or shapefile format. Download a file for the state of Oregon and add the dataset to a map. If you download the .e00 be sure to follow the steps in Part I to convert the file to a coverage in ArcCatalog.

c. Symbolize the seven counties for Northwest Oregon (Multnomah, Washington, Clackamas, Clatsop, Tillamook, Hood River and Columbia.) differently than the rest of the state. You can do this a few ways (some hints: extract to new dataset, definition query, create layer file, symbolize for unique features). Explain what process you used to symbolize these counties differently, knowing that it will require multiple steps.

d. What projection is the Oregon County dataset in? Where did you find this information?

e. The projection is not entirely appropriate for a map displaying just the state of Oregon (notice the east/west distortion). Define the Projection to the cd41_d00 (Oregon counties) based on your answer in the previous question. What tool did you use to define the projection?

f. After defining the projection of the County dataset, find a projection for the dataframe that works well for the state of Oregon (hint: you want to find something local to Oregon that preserves shape – a conformal projection). What tool did you use to change the projection?

g. What projection did you choose?

h. In layout view: add a title; label the seven counties; include your name, north arrow and scale bar; and anything else you need to create a presentation quality map.

i. Print the map or export to a .jpg/.pdf and turn in/email.

2. Return to the Geography link and select TIGER page. What are TIGER files (follow the link ‘2009 Tiger/Line Shapefiles Main Page’ which provides an explanation)? What kinds of datasets are available as TIGER files for the state of Oregon?

3. Follow the Spatial data link below for ESRI Free data and software (TIGER files are also available in a more user-friendly format from the ESRI website).

a. Follow the link for Downloadable Data and choose three TIGER datasets to download. You can choose one county to focus on or choose any of the statewide datasets that are available. Choose datasets that make a map with a purpose or focus.

b. What datasets did you download?

c. Add the three datasest to a map, along with the county file you downloaded in #1.

d. Check out the attribute tables and symbolize each of the datasets in the map.

e. What projection are these datasets in? Define the projection for each of your datasets. Change the projection of the data frame that is appropriate for your map.

f. In layout view add a title (that is descriptive of your map purpose), your name, a legend or labels, north arrow, and scale bar; and anything else you need to create a presentation quality map.

g. Print the map or export to a .jpg/.pdf and turn in/email..

4. You can adapt the tabular data available from the Census Bureau for use in ArcGIS. You will make two maps of Oregon in this section – both must use data from the tables on the Census website and one must be a density map.

a. Start at the Census home page () and follow the links for American Factfinder> Data Sets. Take some time to look through your options for download. **It is large and somewhat confusing, so below is a description of how to download population data. The same process can be used for most other datasets available on the website.**

AN EXAMPLE: Downloading Population Data

b. Find population data for Oregon state by county. To do this, Enter County for Geographic Type, Oregon for State, and then add all counties (see graphic below). Click Next.

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c. On the next page, select Total Population>add>Show result.

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d. Download from the upper menu and select Excel (.xls) under database compatible. Download the file onto your flash drive or other accessible drive.

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e. Open the file in Excel

f. Make necessary edits to your .xls table to prepare it for a join (see Tips).

Tips for Joining Tables

• Before joining the files, you need to make sure that there is a field in both datasets that are identical. For example, if you choose to join the datasets on county name, the names in both files need to be exactly the same – Columbia County and Columbia County, NOT Columbia and Columbia County.

• Make sure each column has only one heading and that there are no spaces in the file name, heading names, or in the folder names for where you are storing your files.

• Make sure that the heading names are not too long – anything longer than 13 characters will be problematic when joining tables.

• Another common error is with the cell format in Excel. Make sure that text columns are stored as text, and that number columns are stored as numbers. It is also very common that excel tables become ‘corrupt.’ If you have tried everything and it still doesn’t seem to be working correctly, try creating a whole new .xls file and starting over.

• Downloading from the Census website sometimes creates “ghost”spaces in the table cells. Look for theses spaces and make sure you eliminate them or else it will affect how ArcGIS reads the file.

g. In ArcMap, add the .xls worksheet (add data) to your map document and then join the table to the county or state dataset (you may have to go back and download a new boundary file as you did in #1), using the common attribute between the shapefile and the .xls table.

h. Classify your newly joined dataset to make your two maps. Remember on your density map that you will need to normalize your data by area.

Calculating Area

If your datasets do not have area as an attribute, you can easily calculate area for a polygon file (in this case…County or state). Open the attribute table and under options, add field. I suggest naming the field area_(unit of measure). For example, area_sqmi. Follow the wizard, changing the data type to 'double' and specifying the other prompted information. After the field is added, right-click on the column and click Calculate Geometry. A wizard pops up that walks you through the steps for calculating area. **Make sure your map and/or dataset is in an equal area projected coordinate system (for example - Albers equal area) and NOT in latitude/longitude if you are calculating area.**

i. What is the difference in calculating area when in a geographic or projected coordinate system?

j. What projection did you use to calculate area for the density map?

k. What projection did you use to display your final maps (aka – what projection is your data frame in)?

l. In Layout view, add a legend, your name, labels, a title, north arrow and scale bar; and anything else you need to create a presentation quality map.

m. Print the map or export to a .jpg/.pdf and turn in/email.

To Add a Legend

Make sure you are in layout view, then select Insert then Legend, and follow the steps in the legend wizard. After you have used the legend wizard, you can still change its appearance. To do so, right click on the legend and select Properties.  To change the names of the files in the legend, simply change the name of the file in the table of contents by single clicking on it.

If you want more control over the look and mobility of your legend, right-click and go to 'convert to graphics.' This breaks the connection between your map data / table of contents and the contents in your legend.

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