I am facing a problem, my shapefiles are in a GCS WGS 1984 and I have to add a new shapefile that is in a projected coordinate system NAD 1983 UTM Zone 8.

I have tried changing the projection to the GCS, and changing my GCS to a projection... but nothing seems to work.

I took a look to the similar questions and I tried changing the coordinate system and/or the projection with the "projections and transformations" tools (project). I also tried to project the files too.

The second image shows the shapefile I want to add to my map.

enter image description here

shapefile I want to add to my map

I am new in this community and I am also a new user of ArcMap.

  • How did you attempt to transform the coordinates? Did you try this method: victoria.ac.nz/sgees/pdf/projection-transformation-guide.pdf
    – ed.hank
    Commented Oct 1, 2015 at 13:58
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    Welcome to GIS SE. As a new user please be sure to take the Tour. Please edit the question to specify whether you tried to redefine the existing projection or whether you tried to reproject. Please use exact tool names with shapefile names and include any errors or describe results in the text of the question.
    – Vince
    Commented Oct 1, 2015 at 13:59
  • I took a look to the similar questions and I tried changing the coordinate system with the "projections and transformations" tools (project). I also tried to project the files too. I am missing something ....
    – Maria
    Commented Oct 1, 2015 at 14:12
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    @Maria ArcMap will display your data from two different systems correctly without any re-projecting provided that the original data hasn't had its coordinate system defined incorrectly. This behavior is called "on the fly" projection, and is great, however it takes more computer resources than if the data is in the same CS. If you truly need to make sure that both data sets are in the same system then the only geo-processing tool you need is call "Project". As long as your data has a coordinate system already associated(which it sounds like it does) this will do what you need.
    – GeoJohn
    Commented Oct 1, 2015 at 14:34
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    UTM zone 8N is just wrong. It should be zone 18N. However, the coordinates don't look right to me for UTM. I think it's MTM 8. Try redefining that data's coordinate system in ArcCatalog, or Define Projection Tool.
    – mkennedy
    Commented Oct 1, 2015 at 19:53

2 Answers 2


ArcMap has this wonderful feature called on-the-fly transformation. Once your first layer is added to a blank fresh map (e.g. a new MXD), the map takes the layer coordinate system (more precisely spatial reference). Any layer added after the first layer, will be automatically transformed to the map spatial reference, in order to overlay with the first layer.

Based on your question it seem you are trying to overlay two layer with different coordinate system. You may have already messed the coordinate of your original data by applying different transformation. I suggest you to receive the layers from original source again.


Oh Canada! Your strange and awkward projections!

It looks like your data is actually in MTM (Modified Transverse Mercator) projection. Not since Gauss-Kruger has a Transverse Mercator projection caused so much confusion with UTM.

You probably reprojected the data, because those XY coordinates in your attributes with the UTM 8 projection would put your points closer to the Canada/Alaska border.

I would re-create the data based on your XY values, then define the projection as "NAD 1983 MTM 8" instead. That should put those data points closer to Montreal.

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