Introduction

I have been compiling ownership shares and Herfindalh-Herschmann Indexes(HHIs) for various metropolitan areas throughout the US and this time, I am posting ownership shares for Wake County, NC at the Census Block Group level. To compile ownership shares, I use assessor data that for each parcel in Wake County includes the parcel’s number of units, land-use, and owner. The data are sourced from the Wake County assessor page. Since the assessor data were not geocoded (ie just address, no lat/lon data), I paired it with geocoded parcels from NC onemap.

What I found particularly striking about Wake County is how competitive the ownership structure is. Compared to Milwaukee or Los Angeles County, Wake County has virtually no neighborhoods in which a single owner dominates the area. I don’t have data on Durham or Chapel Hill at the moment but it would be interesting to see how Duke and UNC areas compare. Nonetheless, it is almost certain that if we see any funk in rents or the like in Wake County, it is probably not due to the residential ownership structure.

Map of Wake County HHIs at Block Group Level

If you click on individual block groups, there’ll be some additional details displayed.

leaflet

Under the hood

There were some data losses in the merger of the assessor and parcel data (ie lost 11,500 of 360,000 observations). Importantly, we must remember that regardless of the source for your real-estate data, there are bound to be a fair share of errors in the data resulting in observation losses. Whether these losses are random enough to retain near-population representation is its own exercise and I won’t delve into. Let’s treat these as best-we-can-do estimations of ownership shares. Finally, I note that ownership shares are always underestimated due to the way property ownership is structured (ie one owner, multiple LLCs).

Interactive maps are created with the help of Leaflet. To see the code used to create these maps, I posted the python and R files on GitHub.