I have a county's worth of census tracts, and I need to combine adjacent tracts into larger polygons. Here's an example of what I'm looking for:four census tracts combined into a single polygon This is four smaller tracts combined into a single large polygon.

I have used Dissolve, but that outputs a single polygon for the entire county which is not helpful for my purpose.

My preferred solution would take a county's worth of census tracts, say 500 or so, and combine them into 200 polygons, without gerrymandering any single group of tracts.

This could be done by hand but I will be doing this for multiple counties.

I'm using ArcMap 10.4.1

  • 1
    Please edit the question to include a graphic that shows what you mean. It is not topologically possible to dissolve two neighboring polygons and retain the line between them (and this is enforced in the I/O module, so there's no way around the constraint). So long as you aren't trying to violate topology, Dissolve will act based on your attribute constraint.
    – Vince
    Nov 4, 2016 at 23:03

1 Answer 1


Take a look at the Grouping Analysis tool, if available to you. This tool assigns polygons to groups based on the constraints you input, and creates a new field to store this information. You could then run the Dissolve tool on your polygons using this new group field as the Dissolve field.


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