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I'm trying to merge the geometries and attributes of a TIGER census block shapefile with those of a vector land cover shapefile. However, I'm not getting the results I want. Whenever I run Union in QGIS, I get one geometry or the other, not a combination of both. When I open up the attribute table, both entries are there but they are separate not merged. Which geometry I get seems to depend on which one I select first in the Union window. Can anyone tell me why the geometries and attributes are not merging?

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    Can you confirm which CRS' the two datasets are in? I notice you're using a User defined projection with "On-the-fly" reprojection enabled for the view window. Would have to test later today whether two different projections could cause this behaviour.
    – Phil G
    Aug 21, 2017 at 11:47

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From your description I understand that you need to merge items from the same layer. If you want to merge items in the same layer make sure that the "Advanced Digitizing Toolbar" is marked be clicking on the right bottom in the muse in the area of the Toolbars enter image description here Now you need to mark the item you want to merge enter image description here Once they are marked use the "Merge Selected Features" and press "O.K" (it's in Hebrew on me screen, so maybe in English it will "Approval" or something similar)enter image description here Now all the items that was overlapping are transformed into one merged item enter image description here You also can use the "Dissolve" option in the Vector Toolbar.enter image description here

Using this option will make you a new temporary layer with the overlapping without changeling the old one. You need to save the new layer or alas it will be deleted once you close the project. enter image description here

The union option is used for merging different layers. It will make a new layer from the two different layers. enter image description here

The overlapping items will be combined into one, but they all will have a different row in the attribute table enter image description here

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  • "I'm trying to merge the geometries and attributes of a TIGER census block shapefile with those of a vector land cover shapefile."
    – Phil G
    Aug 21, 2017 at 11:43
  • If the attributes are not the same, tray to make a new layer with less data and merge them. After this, save it all as CSV and add more data as you like.
    – Nitzan Matan
    Aug 21, 2017 at 12:31

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