{"id":56,"date":"2018-07-06T15:29:32","date_gmt":"2018-07-06T15:29:32","guid":{"rendered":"http:\/\/sarahjpurcell.sites.grinnell.edu\/sandbox_clone\/?page_id=56"},"modified":"2019-10-02T16:29:52","modified_gmt":"2019-10-02T16:29:52","slug":"arcmap-and-gis","status":"publish","type":"page","link":"https:\/\/his100.sarahjpurcell.sites.grinnell.edu\/spring-2021\/tutorials\/arcmap-and-gis\/","title":{"rendered":"ArcMap and GIS"},"content":{"rendered":"

This tutorial was written by Katherine Walden<\/a> (Digital Liberal Arts Specialist, Grinnell College). The tutorial framework was created by Sarah Purcell (L.F. Parker Professor of History, Grinnell College). Tutorial instructions were co-authored by Martin Toney, a student workers in the Grinnell College\u2019s Data Analysis and Social Inquiry Lab<\/a> and Sophia Gates Stern, student mentor for this class.<\/p>\n

This tutorial was reviewed by Gina Donovan<\/a> (Instructional Technologist) at Grinnell College, and edited by Lauren Frankel, a student worker in Grinnell College\u2019s Data Analysis and Social Inquiry Lab<\/a>.<\/p>\n

This tutorial uses data generated by Cameron Blevins<\/a> and posted on his personal site.<\/p>\n

\"Creative<\/a>
\nArcGIS Tutorial is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License<\/a>.<\/p>\n

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ArcGIS<\/a> is an industry-standard tool developed by geographers in the 1970s. As digital historians have pursued more complex and large-scale spatial analysis projects, ArcGIS is a tool frequently used to visualize and analyze spatial data. The ArcGIS Online platform (not covered in this tutorial but featured in many digital mapping projects) allows data analyzed and visualized in ArcGIS to be interactive and publicly-accessible. We will continue working with Cameron Blevins’s postal data<\/a> for this tutorial.<\/em><\/p>\n

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Data:<\/h5>\n

1-Navigate to https:\/\/sarahjpurcell.sites.grinnell.edu\/digital_methods\/files\/cb_2016_us_state_5m.zip<\/a> in a web browser. .<\/p>\n

2-Save the folder to your Desktop and extract the contents.<\/p>\n

3- This folder will contain a folder <\/strong>(cb_2016_us_state_5m) and CSV file<\/strong> (1871_PostmasterSalary_Data.csv)<\/p>\n

4-Open the cb_2016_us_state_5m folder.<\/p>\n

5- Explore the file extensions, and open the CSV file (1871_PostmasterSalary_Data.csv) to review the structure of the postal data.<\/p>\n

A note on file types:<\/p>\n

ArcGIS draws data on a map using shape files (.shp). A Shapefile is actually comprised of a package of individual files, but ArcGIS reads all of\u00a0 those files together as a Shapefile. Once in ArcGIS, Shapefiles become part of layers. ArcGIS can read other file types (CSV, GeoJson, KML), but the program needs to turn that data into a Shapefile in order to save, analyze, and export it.<\/p><\/blockquote>\n

Starting ArcMap and Importing Data:<\/h4>\n

6-To open ArcMap, go to Start<\/strong>, then type “ArcMap” into the search bar. Click on the globe icon that pops up to start the program.<\/p>\n

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7-Click on the Blank Map<\/strong> icon, and the program will open a blank ArcGIS map project. Save this project as “GIS_Tutorial” or another descriptive name of your choosing.<\/p>\n

Importing Shapefiles into ArcMap:<\/h5>\n

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8-Click on the Catalog<\/strong> button on the right-hand side of the window to open ArcCatalog<\/strong>, ArcMap’s program for connecting to files on your computer. ArcCatalogue can be run independently or within ArcMap, and locates files on your computer using folder connections.<\/p>\n

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9-Click on the “Connect to Folder” button near the top of the Catalogue window. Navigate to the Desktop<\/strong> where your cb_2016_us_state_5m folder<\/strong> is located. Click on the folder and select OK<\/strong>. The folder will now appear in your catalogue window.<\/p>\n

10-Click on the “+”<\/strong> symbol next to the folder, which will expand to show the files included in the folder.<\/p>\n

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11-Locate the cb_2016_us_state_5m.shp<\/strong> file, then drag it into the large blank canvas in the middle of the main window. You should now see a U.S. state map drawn in the main canvas.<\/p>\n

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12-Save the project by clicking the floppy disc icon<\/strong> in the top-left.<\/p>\n

\"\"<\/a>
\n13-Go back to the Catalog<\/strong> window, and add another folder connection to your Desktop<\/strong>, where the 1871_PostmasterSalary_Data.csv<\/strong> file is located. Drag the CSV file to the left-hand side of the ArcMap window, under Table of Contents<\/strong> and Layers<\/strong>.<\/p>\n

14-Save the map project.<\/p>\n

 <\/p>\n

Another note on file types:<\/p>\n

ArcGIS loads shapefiles and uses them to create layers. Within the Table of Contents, you will see the shapefiles and data that have been added to the project.<\/p><\/blockquote>\n

Adding data points to the map:<\/h5>\n

15-Right now, the cb_2016 shape file<\/strong> is drawing shape outlines, but the 1871_PostmasterSalary_Data CSV file<\/strong> does not have any spatial data to display.<\/p>\n

16-Right click on the CSV file in the Table of Contents<\/strong> and select Display XY Data… <\/strong>from the dropdown menu.<\/p>\n

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\n17-On the pop-up screen, double check that Longitude<\/strong> is selected in the X field and Latitude<\/strong> is selected in the Y field. No value is needed for the Z field.<\/p>\n

18-Click OK<\/strong>, and click OK<\/strong> again after the Object-ID Field error pops up.<\/p>\n

\"\"<\/a>
\n19-The points from the CSV file have been added to your map as an Events layer<\/strong> (see image above) but needed to be saved as a Shapefile.<\/p>\n

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20-Right click on the Events layer<\/strong> and select Data->Export Data.<\/strong> A dialogue box will pop\u00a0 up prompting you to choose the export features and coordinate system.<\/p>\n

21-Leave the Export<\/strong> as the default and select “the data frame”<\/strong> for the coordinate system.<\/p>\n

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22-Rename the output feature class to Postal_GIS.shp<\/strong> and click OK.<\/strong> A window will pop up asking if you want to display the exported data as a layer–click Yes.<\/strong> A Postal_GIS layer<\/strong> should now appear in your Table of Contents.<\/strong><\/p>\n

23-The checkboxes next to layer names allow you to decide which layers are drawn on your map. Right click on the Postal_GIS.csv Events<\/strong> layer and the Postal_GIS.csv file<\/strong> and select remove to remove these layers from your project.<\/p>\n

24-Save the project.<\/p>\n

A note on navigating ArcMap:<\/p>\n

\"\"<\/a><\/p>\n

By this point, you may want to explore your map in more detail. The “+” symbol on the main page allows you to zoom in, and the “-” icon is a zoom-out option. The “hand” lets you drag the map around, and the i icon lets you see the dated represented by a specific point.<\/p><\/blockquote>\n

Customizing your display:<\/h5>\n

25-Right now, the geographic information is being drawn on the map according to ArcMap’s default settings. The Symbology<\/strong> property allows us to customize how data displays on the map.<\/p>\n

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26-Right click on the Postal_GIS layer<\/strong> and select Properties<\/strong> from the dropdown menu. Click on the Symbology<\/strong> tab, and select Quantities->Graduated<\/strong> colors under the Show<\/strong> menu on the left-hand side of the Symbology<\/strong> window.<\/p>\n

27-Categories<\/strong> would recolor map points by a specific data field, and Quantities<\/strong> colors map points by calculating quantities in the data.<\/p>\n

28-In the Value<\/strong> field, select PM_Salary<\/strong> from the dropdown. ArcMap will use the values in the PM_Salary field to determine numeric ranges.<\/p>\n

29-The Color Ramp<\/strong> dropdown gives you additional options for coloring your data points.<\/p>\n

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By default, ArcMap calculates the ranges using Jenks or Natural Breaks. Click the Classify icon to choose other ways of calculating these intervals.<\/p>\n

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30-Leave the other options at their defaults and click OK<\/strong>. Notice map points have changed color based on ranges in the postmaster’s salary. The Table of Contents<\/strong> now includes a legend under the Postal_GIS layer<\/strong> that specifies the salary range for each color.<\/p>\n

31-Save your project.<\/p>\n

Additional display options:<\/h5>\n