There was a little Senate election in a place called Massachusetts the other day — you’ve probably not been able to avoid it. Republican Scott Brown defeated Democrat Martha Coakley by nearly 5% — yet, what makes this election result so astonishing is the recent political history of the State. To call Massachusetts strongly Democrat is not too dissimilar to calling the Vatican strongly Catholic or RSL clubs strongly monarchist. The current state House of Representatives consists of 144 Democrats, 15 Republicans and an Independent. The current state Senate on the other hand is a comparative hotbed of Republicanism, consisting of 35 Democrats and 5 Republicans.

The Democrats have held both Massachusetts Senate spots in the US Congress since 1979, and have held one of those spots — the Class 1 Senator position — for all bar six years since 1927. Not only has this Massachusetts Class 1 Senate spot been something of a modern Democrat institution, it has been filled by Kennedys for 54 of the past 56 years, starting with JFK.

So when Coakley, the recent Attorney-General of Massachusetts, lost the Kennedy’s Senate spot to a Republican — you sort of get the gist of why it’s all turned into such a media and political circus.

The most interesting thing to come out of the election was the way the vote changed and where. If we compare the numbers of votes that Coakley and Brown received in each of the 351 towns and cities in Massachusetts, and compare it to the votes received by Obama and McCain in the 2008 Presidential election, it tells a little story.

MAchart

The 45-degree line in that chart shows what would have happened if Brown and McCain or Coakley and Obama received exactly the same number of votes. Were that to occur, we would expect to see the results of each of the 351 towns and cities running up and down that line (although there’s a few cities not on the chart, such as Boston with it’s 150,000 votes — they’ve been removed not because they bucked the trend, but because their addition would have stuffed the graph due to the scale involved).

Brown received an extraordinarily similar number of votes as McCain received — about 1.17 million compared to McCain’s 1.1 million. But while the Republican vote effectively stood still, the Democrats vote crashed, with Coakley receiving only 1.01 million votes compared to Obama’s 1.89 million two years ago.

The turnout figures tell some of the story — while 73% of registered voters turned out for the Presidential ballot, only 54% of registered voters turned up for the Senate election.

Most of those who stayed at home were clearly Democrats.