I was just wondering if it was possible to change the projection of only certain objects in a shapefile, while the others remain the same. I have to insert points onto a map, and some of them are in a projection called MTM 10, while others are in MTM 13. In order to get the points into the shapefile I'm using, I have to copy and paste them from an imported AutoCAD drawing. The points are supposed to be in the same shapefile, but everytime I change the projection, they all move. Is there a way to get around this and only change the projection of a few points?

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    Shapefiles have exactly one coordinate system. You need to reproject before adding to the file.
    – Vince
    Commented Mar 16, 2015 at 14:07

1 Answer 1


you should use the merge tool (or the append tool) to copy your points from one dataset to the other dataset. Launched from ArcGIS, the selection will be honored + this will reproject on the fly. Your points are probably moving because their projection was not defined. This can be done using the define tool. At the end, only one coordinate system is possible per shapefile.

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    @EmilyF Note the Define tool is for assigning a CRS to data that doesn't have one or is incorrect. If you bring in your MTM 10 points and assign them that CRS, you would not use the same tool to then change it to MTM 13 to bring in the other points. You'd use the Project tool to reproject your MTM 10 points to MTM 13 and then add those points, then you'd have them all in MTM 13 (or could Project to whatever else). Just changing the properties of the file is similar to Define - it doesn't move or adjust coordinates, it only changes their reference system.
    – Chris W
    Commented Mar 16, 2015 at 18:47

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