Moving Maps Online
In this tutorial, we’ll explore one method of moving your digital maps online using the web-based tool ArcGIS Online. For this exercise, we’ll be mapping data from George Reid Andrews's Afro-Latin America, 1800–2000, which lists the dates that countries in the Americas passed slavery abolition laws. We’ll begin with a brief task in QGIS of joining the Andrews data to a country boundaries file. Then we’ll take the file we export from QGIS, load it into ArcGIS Online, and visualize it in two different ways.
Before you begin, you should make sure that you’ve claimed your UCSC-affiliated ArcGIS Online account (this is different to their free public accounts). All students in LALS 194 should have received an email with the subject “An invitation to join an ArcGIS Online organization, UC Santa Cruz” that includes detailed instructions on how to do this. Contact your instructor or the DSC if you did not receive this email or have trouble logging in.
Before we move our mapping data to ArcGIS Online, we need to assemble the data file in QGIS. This will require us to join a country boundaries file to the data on abolition dates we have from page 57 of George Reid Andrews's Afro-Latin America, 1800-2000. Note that we haven't included data for countries that didn't gain independence until the late-nineteenth or twentieth century and thus abolished slavery under colonial rule (i.e. Canada, Belize, Guyana, Suriname, and French Guiana).
Now we’ll join the spreadsheet data to the country boundaries file.
Now select the Americas layer, right click, and select Open Attribute Table. You should see the columns of data from the Andrews_p57-updated spreadsheet added to this layer’s data. Note that not all countries from the boundaries file will have data from the Andrews spreadsheet.
Our last step is to export this joined data as a new file that we can load into ArcGIS Online.
This step in the process assumes that you’ve set up an ArcGIS account that’s affiliated with UCSC. Navigate to https://www.arcgis.com/ and login with your credentials. (Contact your instructor or the DSC if you did not receive an email prompting you to set up the account or have trouble logging in.)
Once you’ve logged in, we’ll begin by loading the new data file into your account and getting it ready to map.
(Note that for now we are only visualizing the date of final abolition, but with the data we have we could alternatively visualize the end of the slave trade or the free womb laws. In order to highlight either one of these, we would simply make that selection in the drop down within this “Enable time” menu.)
Now your data should be ready to map with time animation. The next and final step will be to create a map with this data.
There are a few ways to create a new map in ArcGIS Online, including simply clicking Map in the topmost menu. But since we’re already viewing the data that we want to map, it will be faster to “Open in Map Viewer” in the right hand menu.
Now let’s do some additional styling and get our time animation feature working.
Now hit play on your timeline. You should see countries appear on the map according to the date they passed abolition legislation.
The time series map is one useful way to visualize this data and can be shared with others for viewing directly in the ArcGIS Online interface. But unfortunately the time animation feature does not work within StoryMaps, which is where you will ultimately want to display this map. For that reason, let’s go through the steps to visualize this data in a slightly different way with a color ramp to indicate the year sequence.
Now you have a map that shows countries colored from darker to lighter based on when they passed slavery abolition laws. This will display correctly in StoryMaps
When you've finished your map, you can share it in a couple different ways.
You may also notice the option to Create a Web App from your map. We won't be discussing that option here, but the next tutorial will deal with one of those apps—StoryMaps.