US congressional election - some trends

I've always been fascinated by elections and election results, and so the recent American 'mid-term' elections caught my eye.

I think that the most significant results are the ones for the House of Representatives - for two reasons. First, because the whole of the US votes in these elections (as it does every two years), whereas the elections for the Senate and for governorships only involved some states. Secondly, because there are 435 different races - as opposed to only 37 for Senate and gubernatorial elections - they are a much larger sample of political views.

If one graphs the performance of the Democrats and the Republicans over the past 40 years, it looks something like this:


(In fact, the 2010 results are not yet finalised. It is expected that 193 Democrats and 242 Republicans will be elected - but that might vary by one or two.)

There are two things that interest me.

The first is that over the past 40 years, the general trend seems to have been for the Republicans to have gained in numbers. In the 1970s and 1980s, the Democrats always had significant majorities, and even when Republican presidential candidates won 'landslide' victories in 1972 and 1984, it didn't translate into great results for the Republicans in the House. The Reagan years (1980-88) may be remembered as great years for the Republican party, but in some ways, they weren't. Americans seem to be much less likely simply to vote for the party than British voters; Americans tend to look at the individual they are voting for.

The first is that the last three elections (2006, 2008, and 2010) have seen very sharp swings - first to the Democrats, then back to the Republicans - with the Republicans doing rather poorly in the 2006 (largely because of the Iraq war) and 2008 (a combination of war, the economy, and the Obama factor) - and the Democrats doing poorly in 2010 (because, I suppose, of, er, well, the war, the economy and the Obama factor).

And the fact that the Republicans have had their best House election since 1946 (when they won 246 seats) does seem to indicate that either the trend is going their way, or that the Tea Party movement has not put the voters off, or both.