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I was given precinct level election data but need to make a map at the county level. The precinct data does not have any Counties listed in the attribute table, so I took a county layer and did a spatial join with my precinct data. I did Target feature: County and Join feature: Precinct. Join_One_To_One. Selected the "County_Name" feature to join feature. Set my merge rule to "join." The new attribute table for this join shows the "vote totals" per county as completely wrong - it seems like it's only bringing in one precinct per county and not adding all of them together. For example, Los Angeles County shows 700 votes when it should be hundreds of thousands. I tried doing a spatial join the other way (Target:Precinct and Join Feature: County, and the vote totals seemed correct! But then, I'm not sure how to make a County level map when the view is all individual precincts.

Can anyone help me with this?

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  • Sounds like you could just use the dissolve tool and dissolve the polygons on the county name field. This would dissolve the precinct borders and just leave the county borders. Otherwise, you could use the Join Field tool to join the vote totals field to the counties layer from the spatial join layer based on county name or id.
    – jdavid05
    Oct 2 '20 at 21:57
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Spatial Join is probably not what you need, I would suggest using Dissolve it will allow you to SUM everything based on a specific column. See the ArcGIS documentation linked above.

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