Skill Drill: Creating a CSV Table to Import As XY Data


In this scenario, several sites were proposed as potential replacement locations for the new fire stations. These locations must be evaluated to determine the top three choices for the Arcata Fire Protection District and related regions.

name latitude longitude
Sunset Fire Station 40.879955 -124.085222
Samoa Fire Station 40.865417 -124.089811
Bayside Fire Station 40.857932 -124.072109
Community Park Fire Station 40.86473 -124.079219
Alliance Fire Station 40.874875 -124.090217
Janes Fire Station 40.901818 -124.091445
Giuntoli Fire Station 40.904993 -124.078412
West End Fire Station 40.903426 -124.071856
Central Fire Station 40.930078 -124.101093
Hiller Fire Station 40.942134 -124.105222
Railroad Fire Station 40.945557 -124.105554
Pickett Fire Station 40.944498 -124.097953
Grange Fire Station 40.977792 -124.100109
Murray Fire Station 40.956121 -124.095253
Fickle Hill Fire Station 40.867667 -124.073769

 

In Microsoft Excel, create a CSV table with the following field headers: name, latitude, longitude. Enter the name, latitude, and longitude values show above in the appropriate fields. Save as a CSV table and close Excel.

A GPS receiver set to WGS 1984 was used to obtain the geographic coordinates in decimal degrees. It’s important to remember that each geodetic datum as a unique set of latitude and longitude values. For example, the latitude and longitude values for your home using the North American Datum of 1983 will be different than the latitude and longitude values using the North American Datum of 1927. Likewise, the World Geodetic Datum of 1984 (WGS 1984) will use yet another set latitude and longitude values to define the location of your home.

Like most latitude and longitude values you will obtain from the internet or from a GPS receiver, the decimal degrees in this are currently in the geographic spatial reference system WGS 1984. When adding XY data, the ArcGIS software only reads the decimal degrees. It is unaware to which spatial reference system these decimal degree values belong. ArcMap will assume, incorrectly, that the spatial reference is the same as the dataframe.

An image of the Add XY Data dialog box
You can locate the spatial reference ArcMap will use under the Description. To re-define the spatial reference, click on the Edit button to select the correct spatial reference.

You must indicate in the Add XY data dialog box that this series of decimal degree values belong to the WGS 1984 spatial reference system. If you do not, your proposed sites will likely end up somewhere in the ocean.

An image of the Warning Dialog Box in ArcMap.
The ArcGIS software will remind you that you will still need to export the events layer in order to create a permanent shapefile that includes database functionality.

After adding XY data, the ArcGIS software will create a temporary events layer. In many ways, the events layer appears to be similar to a shapefile. However, it is only a temporary representation and does not have an associated database.

An image of the proposed location events layer.
An events layer is temporary and should be exported as a shapefile.

Export the events layer as a shapefile and save it to your working folder. You should now have a shapefile of the proposed locations in the WGS 1984 spatial reference system saved in your working folder. Next use the Project tool to create a copy of the data with the NAD 83 UTM Zone 10 spatial reference system. Add the layer with the correct spatial reference to your Table of Contents and remove the old version.