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I am trying to add a shapefile that is a map of Manhattan wards and then plot some latitude-longitude data points over this map. I'm new to ArcMap and GIS in general.

Here is exactly what I am doing:

I have a shapefile that shows Manhattan wards when I "Add Data" it into ArcMap. I then go to Geoprocessing -> ArcToolbox -> Data Management Tools -> Projections and Transformations -> Define Projection. I then input my .shp file and select NAD 1983 State Plane New York Long Isl FIPS 3104 (US Feet) for the coordinate system. After I do this, my shapefile displays just fine.

I then "Add Data" a .csv file which contains addresses and the latitude and longitude for these addresses. I then right-click on this layer and select "Display XY Data...". I then make the "X Field" latitude and the "Y Field" Longitude and use the same coordinate system as mentioned above. However, the points never display. I still only see the wards shapefile displayed. Both layers are present in the Layers menu, but only one is actually being displayed.

Alternatively, if I restart ArcMap and add the points first and display the XY data, I see that the points are displayed. After I add the shapefile, the shapefile does not display. I only see the points. It seems I can always display one thing but not the other.

Any thoughts on why this is happening?

I am using ArcMap version 10.2.0.3348 on a Windows OS.

  • Are you calculating new geometries for your transformed .csv file? I posted once a [tutorial](http://gis.stackexchange.com/questions/20572/layers-having-the-same-coordinate-system-should-overlap-but-they-dont-whats/54601#54601) in the GIS SE site that might help you. – Andre Silva Jan 19 '14 at 01:33
  • 'I then make the "X Field" latitude and the "Y Field" Longitude' - you mean the other way around, yes? Latitude is the y axis. :) – Juffy Jan 19 '14 at 22:15

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I assume you are trying to overlay different spatial reference systems without telling arcmap which ones you use, so it cant reproject them to fit together.

When you say "latitude" and "longitude" you normally mean a geographic coordinate system like WGS84. Whilse X and Y often refer to a projected coordinate system like NAD. You defined NAD for both layers...I think you should define a geographic coordinate system for your CSV File, if it really contains geographic coordinates.

ArcMap uses the spatial reference system of the first layer which is added as the display SRS (you can change this afterwards for sure), thats why you saw your shapefile first and after restart and adding the points saw the points first.

If every layer has its SRS defined correctly, ArcMap will reproject them automatically to fit your display SRS. If you define the wrong SRS for one layer, Arcmap will do nothing for sure, because there is no need to reproject a NAD layer to NAD (although the coordinates have a completely different value domain and your points get drawed somewhere else....check this by right clicking on the CSV layer and "Zoom to Layer (extend)".

To make it more complicated: Because NAD83 and WGS84 rely on different geodetic datums, you have to transform. You find a predefined set of transformation parameters when you right click on "layers" in the "table of contents" on the left and select "properties". On the "coordinate system" sheet you see the "Transform" Button where you can select the transformation parameters which should be use to get from NAD83 to WGS84 and vice versa. A more detailed description can be found at this GIS SE

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