I have two data sets: one for Thurston County, Washington and one for all of Washington state. I created a map of hydrology features in Thurston County, and now I want to take the data from the Washington state data set and overlay it on top of the Thurston County data set, so that all of the WA state data points inside the county boundary are added, but nothing else is. How would I do this in ArcGIS for Desktop?

I'd be interested in instructions on how to do this, but just knowing if there is a name for this type of operation so I can search for more references would be helpful.

  • Note: I'm just starting to learn how to use GIS tools, so please assume a very basic level of knowledge. – J. Taylor Oct 6 '15 at 15:15

Two ways: use select by location or intersect. Good tutorials on ESRI's site in the hyperlinks, so I won't give instructions here.

  • Yes, select by location and intersect are exactly what I was looking for. Thanks! – J. Taylor Oct 6 '15 at 16:24

Also, my original question had also asked how to do this in QGIS, but somebody came and removed that for some reason ... for people who are interested in doing this using QGIS, I found how to do this from this Stack Overflow post: Selecting features within polygon from another layer using QGIS?

You can use the "Vector->Research tools->Select by Location" and tick the "Use selected features only" checkbox.

If you want to actually export the points which intersect your selected polygon to a new shapefile then "Vector->Geopressing tools->Intersect" and again tick the "Use only selected features" checkbox. The input layer will be your points layer, and the select layer will be your polygon layer.

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