Redistricting "Blocks"

[Sol]

One thing that I've noticed is that UCCs, along with various other requirements that a redistricter might use, create blocks of territory that all have to be in the same district. A good example is NC, where these counties are required to go together, to keep the Lumbee and Fayetteville UCC in one district:



Are there any others? Does anyone have any pointers on handling them well?

[Miles]

I think we've agreed to disagree about southeastern NC, as I think Robeson County should be in CD7.

For LA, I always try to keep St. Tammany Parish should be kept with the suburbs in northern Jefferson Parish. I also like to keep Terrebonne and Lafource Parishes together. The current CD3 (and really the former CD7) is a pretty logical and clean district, so thats always a good starting point for southern LA.

[Gass3268]

In Wisconsin it was always common practice and tradition to keep Marathon, Portage and Wood counties together. 

[muon2]

I think there are two schools of thought on the splitting of UCCs. They are the regional method and the chop method.

If one takes a regional approach then there are no breaks in UCCs (and MCCs) and one forms strictly whole county regions which may contain two or more CDs based on the size of the UCC. A regional plan is judged on the inequality of the regions measured by the average absolute deviation of the region populations from their quota and the erosity of the regions. Chops are made to equalize population after regions are formed and judged. The number of regions equals the number of CDs plus the number of UCCs that are larger than a CD minus the total number of CDs needed to cover those large UCCs. For example NC has 13 CDs and two clusters larger than a CD - Charlotte which needs three and Raleigh which needs two. Thus a regional approach for NC uses 10 regions (13 + 2 - 5).



If one takes the chop approach one treats UCCs and MCCs like another form of county for counting chops. Chops less than 0.5% of the quota are microchops and don't count in the chop total. The goal is to minimize both the chop and erosity scores and then population inequality is used to break ties.

However, based on the UCC/MCC definition there's no penalty to splitting Robeson NC from the counties to the north and west. A plan that keeps them together and scores well might be preferable from a local choice perspective.