Converting a Multipart Polygon to a Single Line

Question

I am dealing with a multipart polygon shapefile of Canada, where each province is its own polygon. Simply for cartographic purposes I want to display the provincial boundaries as a dashed line but given that shared boundaries are not actually shared (2 lines overlapping) in a multipart polygon I am unable to use a dashed line as it does not line up between the two shapes and is no longer dashed!

My end goal would be to 'merge' those shared boundaries so they appear as a single line rather than two overlapping lines. I have tried dissolving, multipart to singlepart, topology, polygon to polyline and nothing seems to achieve my goal.

Like I said, this is purely for cartographic purposes so the method does not have to be perfect and a MacGyver workflow would suffice. I am running ArcGIS 10.4.1 for Desktop basic lisence.

Answer 1

Use the intersect tool and set the 'Output Type' to 'LINE'. This will return only lines where the polygons intersect:

The polygon boundaries must match for this to work. Here is my example - the red line is the result of the intersect tool:

To get all your lines at once, intersect the provinces with themselves (add the layer twice to the intersect input). Then you get all your lines back in one step.