The red stains spread out across the maps of the US like bruises or the ink blots of a Rorschach test. They are maps of hate speech, as gathered via Twitter and analysed and plotted by a team of researchers led by the Humboldt University geography professor Monica Stephens.
During the 2012 campaign, Dr Stephens noted the surge of racist tweets made about President Barack Obama, and decided to plot those that were sent with a geocode - an electronic pinpoint - to see if some areas appeared to be more racist than others.
In that early project she discovered that two of the hotspots were Mississippi and Alabama, states that voted strongly against the president and have a history of poor race relations.
Intrigued, she and a group of students decided to map hatred across America using the same method - plotting the location of tweets made with derogatory use of terms such as ''nigger'' and ''fag''.
Using a sea of data collected and stored by the University of Kentucky, the team gathered every geo-coded tweet in North America between June 2012 and April 2013 that included one of the hate words, and began the task of reading them one by one to sort out which were genuinely hateful.
''There is often a difference between the N word when it is spelt N-I-G-G-E-R and N-I-G-G-A,'' Dr Stephens explains.
That left them with more than 150,000 geo-tagged hateful outpourings, including 41,306 that used what Americans now call the ''N'' word, and 95,123 that used ''homo''. (Only a very small percentage of tweets are geo-tagged, so this remains a small sample of the amount of tweeted hate speech.)
The team then normalised the number of tweets with the broader population, so that areas with high concentrations of Twitter users, such as Los Angeles, were not over-represented.
Many of those who posted the little messages feeling safe in their anonymity might be surprised at how specific the team's knowledge is of them. Even though Dr Stephens and her staff have maintained the anonymity of the senders, in many cases she can see not only the address of the home from which a particular tweet was sent, but also the room in the home. The individual tweets can be remarkably revealing even in their banality.
Someone called Anthony at an Apple Store in the town of Ardmore, Pennsylvania wanted to know: ''Does the Apple Store only hire homosexuals? (@AppleStore)''.
From Long Beach came the lament: ''They tell us turn out [sic] wetback music down so why can't I say nigger?''
Broadly the maps show that Twitter users in integrated urban centres like Los Angeles and New York tend to use hate speech less than other areas.
The chart of the term nigger reveals that it is used broadly across the country, but more in the east and the west, though with concentrations in areas with histories of division, such as Alabama and Georgia.
Dr Stephens was surprised by how often it cropped up in some smaller rust-belt towns. After the finds were published she was contacted by people who had discovered the maps and who offered some explanation.
In one case racial invective spiked in a small town that had just become home to resettled Somali refugees.
Comparing the maps against each other is revealing, too.
''Wetback'' as a term of abuse is not common but there are two hotspots in Texas, which has been at the centre of an angry debate over immigration reforms that would see the 11 million undocumented immigrants in America, mostly from Mexico, offered a pathway out of legal limbo to citizenship.
One of the surprises for Dr Stephens after the work was published was how angry it seemed to make some people.
''Mostly it was people who thought that their group was subject to attacks but had been ignored,'' she says. That included Christians and Jews, women and men.
She tried to explain that though the team did test hate words directed at those groups, the data was not useful.
Terms like ''bitch'' and ''slut'' were used so commonly, it would take years to read them to sort the genuinely hateful from the affectionate (think ''beyatch'' and slut walks). She considered ''honky'' and ''cracker'' for whites but found the former was used almost entirely positively in regards to honkytonk music and bars, while the latter barely existed.
Instead, she collects the hateful emails sent to her by those who feel ignored by her work, like the man who wrote to her: ''You are targeting white, blue collar people who pay taxes and, hence, your lowly ass salary. Why don't you get a REAL job instead of sucking Uncle Sam's Big Dick. You are not going to have a job for long since we, as taxpayers, are pissed off at paying the salaries of idiots like you that take grant money and produce the Study du Jour. C- - -!!!''
Dr Stephens says she is unbowed by the attacks, and believes her early work in the field shows research into out electronic footprints will prove useful.