US Election 2012 County-Level Results

I've been experimenting with the 2012 US election results at the county level* published on the Guardian Datablog and comparing percentages for Obama and Romney. One of the most striking things is how Obama won in DC (over 91.4% of the vote) and in the Bronx, NY (91.2%). The highest percentage for Romney was in King County, Texas where he won 95.9% of the vote. The image below shows these patterns and also includes some information on race, with % Hispanic and % African-American mirroring, to a large extent, the percentages of voters choosing Obama. It's not really that simple of course, but there is a correlation. One interesting nugget here is the difference in total votes won in counties with the highest voting percentage for each candidate. In the 5 counties with the highest Obama percentage, almost 850,000 voted for Obama. By contrast, in Romney's top 5 counties the total was just under 20,000 voting for him.

Full size version here

What does any of this mean? It means that the Republican Party probably need to think about how to do better in cities, with Hispanics and with African-Americans, but they already know that. Romney was very successful in areas where not many people live but not successful enough in major cities. It's all pretty obvious but it stands out more when you look at it on a 3D map!

*(for the continental United States, so no Alaska or Hawaii for now)

Shannon County, South Dakota: Democrat Stronghold

I've talked about 3D mapping here before, and why I like it, so I thought it was about time for another one. Since the US presidential elections have just taken place I thought I'd look at some of the data and make some maps. I'll post some more when I have time but for now I thought this 3D map showing the ratio of Obama to Romney voters at the county level was pretty interesting, not least because it identifies an interesting high point in South Dakota. 

Click here for a full screen version

South Dakota is a Republican stronghold but Shannon County is the exact opposite. In both 2004 and 2008 it had the highest Democratic voting percentage in the United States (over 85% both times) and in 2012 more than 93% voted for Obama. This might not come as a surprise when you discover that Shannon County is located entirely within the Pine Ridge Indian Reservation and that out of around 8,700 registered voters, 6,500 are registered Democrats. 

One advantage of using a 3D choropleth is that you can often differentiate between places within the same class in a way that is impossible with a normal 2D choropleth. It usually makes it very easy to see places that stand about - such as Shannon County - and it is a powerful way to visualise this kind of data. There are down-sides too (visual occlusion being one of them) but the continental United States is a nice shape with nicely divided counties, so it works well there.

Beyond Shannon County, the Obama strongholds with real weight in terms of population are DC and the Bronx. In both cases Obama voters outnumbered Romney voters by more than 10 to 1 - 222,332 to 17,337 in the case of DC and 264,568 to 24,430 in the Bronx.

More on this kind of thing coming in the near future...

Population Density in New York City

In some recent posts I've been looking at the issue of population density. I did this for London in December and for the continental United States earlier this month. Given the extremely high population density in Manhattan, I thought it would make sense to take a closer look at New York City. So, I took some publicly available NYC GIS data, some 2010 US Census data and went to work. The result is the 3D map image below...

See this image full size

The mapping here is done at the Census Tract level, of which there are about 2,100. These areas have an average population of about 4,000 though there is some considerable variation between areas in that several tracts contain more than 10,000. The spatial patterns above are fairly obvious and, as expected, Manhattan dominates once again. However, the individual Census Tract with the highest population density is actually in Corona, Queens with a figure of 216,000 persons per square mile*.

There's a lot more information on New York City's 2010 Census results on these pages, from the New York City Department of City Planning...

* N.B. It's important to point out here that these areas are much less than a square mile, but I'm using square miles since it is a conventional measure of population density in urban areas).