The Minnesota Senate recount is still unresolved (although Democrat Al Franken seems to be in the slightly better position), but at least we can now be definitive about the outcome in the US House of Representatives.

The Democrats won 257 of the 435 seats, a majority of 69 and a gain of 21 seats from 2006. According to the compilation by the Green Papers , that was based on a Democrat popular vote of 52.8%, or 55% in two-party terms. (The Clerk of the House of Representatives will eventually compile a full set of official figures, but that takes months.)

Coming on top of the big gains in 2006, that’s not a bad result. It’s one of the things that makes Obama’s victory rather more impressive than Bill Clinton’s in 1992: although their two-party presidential vote and electoral college margin are almost identical, in 1992 the Democrats only held their own in congress — in fact they went backwards slightly in the House. Obama seems to have had longer coattails.

Even so, it’s a long way from any sort of record. Jimmy Carter and Lyndon Johnson had much bigger Democrat majorities in congress, which didn’t prevent their presidencies from ending badly.

Over at fivethirtyeight.com, however, Nate Silver argues that the Democrat position in the House is stronger than it looks on paper. He points out that 40 of the Democrat victories were unopposed, as against only 14 Republican. Factoring those in suggests a two-party vote more like 57.5%.

Moreover, the Democrats have a lot more safe seats. Silver calculates that there were 126 districts (including the unopposed ones) where they won by 40 points or more (ie, roughly speaking, with more than 70% of the two-party vote). Here’s how he summarises them:

In general, they were more urban, younger and poorer (although not any less educated) than the country as whole, and contained a significantly higher share of minorities. … Basically, the Republicans aren’t competitive virtually anywhere on the Eastern Seaboard north of Washington, D.C., and virtually anywhere on the Pacific Coast north of Monterey. They aren’t competitive in virtually any dense urban center, or in virtually any majority-minority district (such as the black belt in the South or Hispanic-majority districts in South Texas). Finally, there are a dozen or so districts where Republicans are virtually nonexistent because of the presence of a large College or University.

By contrast, there are only 30 equally safe Republican seats, and 22 of those are in the south. In Silver’s words, they nearly all “fit into a particular template: white, Southern, rural or exurban, lower-middle class (but not usually impoverished), low-mobility, with poorly-diversified economies reliant on traditional sectors like manufacturing or agriculture.”

In one sense, that gives the Republicans an advantage: fewer safe seats means their support is more efficiently spread, with fewer wasted votes. But it also means the Democrats have much more to gain from the redistributions that will take place after the 2010 census, with more votes to shuffle around and create more winnable seats.

And in the longer term, the GOP is facing serious demographic problems. Its strongest areas, as we saw also in the presidential election, are low growth, with ageing populations and declining economies. The most dynamic parts of the country seem to be the ones moving most strongly towards the Democrats.

Nonetheless, these things can change. Even now, the Democrats’ House majority is no bigger than it was immediately before the GOP won back control in 1994. And before the 2004 election, Hendrik Hertzberg, The New Yorker’s political expert, said he did not expect the Democrats to control the House of Representatives again in his lifetime. It happened just two years later.