County by County US Elections Map Results

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Election 2004 Results

Robert J. Vanderbei

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-->Click here for Election 2000 map. Using County-by-County election return data

from USA Today together with County boundary data from the US Census' Tiger

database we produced the following graphic depicting the results. Of course,

blue is for the democrats, red is for the republicans, and green is for all

other. Each county's color is a mix of these three color components in

proportion to the results for that county. Counties shown in black represent

either missing election data or a mismatch between the US Census data and the

USA Today data. For example, the New England states' election return data is

given for each municipality and/or district rather than for each county. Hence,

it couldn't be easily matched with the county boundaries. Click here for a

larger version. Comments:

11/06/04:

Here's a map showing Congressional Districts for all 50 states:congdist.gifIf

anyone can tell me where to get corresponding voting data, I'd be happy to

paint this map in shades of purple. Many thanks to Paul Schlichtman for

assembling the county data for Massachusetts. Suresh Venkatasubramanian, who

work's in Stephen North's department at AT&T, has made a county-by-county

cartogram. My apologies to the many who have written to me in the last few

days. There are simply too many emails for me to respond to them all. But, I

have read each one and considered all suggestions that have been put forth.

Hopefully, my comments in this section address most of the more common

suggestions.

11/05/04:

Here's a version with mountains added to indicate where people live: Click here

for a full-sized version.

Today I received many emails requesting that I make a version of the map in

which the 50/50 even split point is rendered in a neutral color, such as white,

black, or gray. Such an image would make it easy to distinguish a 45/55 county

from a 55/45 county---one is slightly red whereas the other is slightly blue.

Modifying the code to make 50/50 appear gray was trivial. But, I think such a

plot distorts the essential point which is that a 55/45 community is almost the

same as a 45/55 community. I'd rather not introduce artificial devices to

facilitate making such distinctions. Maybe tomorrow I will feel differently.

11/04/04: I've received a flood of emails today. Let me try to answer some of the questions here.

Can you make the areas with high population density brighter than those with low

density? Yes, I tried that. The trouble is that the big cities are so much more

densely populated than everywhere else that the map appears black with just a

few small bright counties. Unfortunately, computer monitors have a dynamic

intensity range of just 256 and this is not enough for an intensity

differentiated map. I experimented with some nonlinear transformations (such as

a logarithmic or gamma-power law) and so doing was able to make a map with

darker, but not black, unpopulated areas. But, this seems even more misleading

because the viewer is told that the intensity represents population density and

then thinks more people live in the unpopulated areas than actually do---the

correct luminosity is virtually black. So, instead, here is a map from the

International Dark Sky Association. It shows quite dramatically where most

people live.

Where did you find the data? The NJ data came from this website at USA Today:

http://www.usatoday.com/news/politicselections/vote2004/PresidentialByCounty.aspx?oi=P&rti=G&sp=NJ&tf=l

The other states came from analogous web pages with "sp=NJ" replaced by "sp=xx"

where "xx" is the two-letter code for a particular state. I used the mouse to

copy and paste the data into 51 separate state files (don't forget DC).

the data into one master file:

all.bko

There are five columns. The first is the state -->

Will you make source-code available? Unfortunately, probably not---at least not

in the near future. One reason is that I use this data for a programming

assignment in a computing course that I sometimes teach---if the source code is

available on my webpage, then I won't be able to assign that programming

assignment any more. Also, I used an eclectic mix of UNIX tools and JAVA

utilities. It would be painful to describe how it all fits together. Can you

warp the counties so that each county's area is proportional to its total vote

count? Such warped maps are called cartograms. There are already several of

these at the state-by-state level on the web. I haven't seen any at the

county-by-county level. A few years ago I collaborated briefly with David

Dobkin and Stephen North on algorithms for producing cartograms. I can say that

making a cartogram with so many individual elements (counties) would be very

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