Never reason from a static coalition

From the Great Depression election of 1930 to the Contract with America election of 1994--so a period of 64 years--the US House of Representatives had a Republican majority for precisely 4 years (two terms): 1947-49, 1953-1955, the terms of Speaker Joseph William Martin Jnr.

Since the Contract with America election, the only non-Republican Speaker has been Nancy Pelosi (2007-11). So, after having a US House of Representatives majority for 4 years out of 64, the Republican Party has since had a majority for 16 out of 20: a majority confirmed, indeed increased, in the recent midterm elections, with the Republicans achieving their largest majority since 1928. [Or, at a State level, since 1920: with the Democrats down to Civil War levels of (lack of) State control.] Suggests that shifts in the electorate have been heading the Republican's way.

Density, diversity and Democrats

Yet, it is very easy to find analyses which will tell you that long-term demographic trends are working against the Republican Party. One of the more striking such analyses is a population density analysis by Baltimore entrepreneur-blogger Dave Troy. With a couple of striking graphs, he points out (in a November 2012 post) that, once population density in a county hits 800 per square mile, it votes Democrat; with such voting increasing the more population density does. Indeed, as density also means diversity, it correlates strongly with racial residence patterns--except it apparently only takes 3% Asian population or 9% Hispanic population to trigger Democrat majorities at a county level. Hence, he concludes that

The real drivers seem to be density and diversity. Density (such as found in cities) corresponds with diversity. Diversity leads to progressive voting behaviour.

The Atlantic magazine took up this theme in a November 2012 article, that the US political divide was a rural-urban one:

The new political divide is a stark division between cities and what remains of the countryside. Not just some cities and some rural areas, either -- virtually every major city (100,000-plus population) in the United States of America has a different outlook from the less populous areas that are closest to it. The difference is no longer about where people live, it's about how people live: in spread-out, open, low-density privacy -- or amid rough-and-tumble, in-your-face population density and diverse communities that enforce a lower-common denominator of tolerance among inhabitants.  

The voting data suggest that people don't make cities liberal -- cities make people liberal.

This divide is how things are trending:

This divide between blue city and red countryside has been growing for some time. Since 1984, more and more of America's major cities have voted blue each year, culminating in 2012, when 27 out of the nation's 30 most populous cities voted Democratic. According to Dave Leip's Atlas of U.S. Presidential Elections and The New York Times, the 2012 election marked the fourth time in the last five federal election cycles that voters shifted away from the party of the sitting president. Despite that constant churn, one part of the electoral map has become a crystal clear constant. Cities, year by year, have become drenched in more blue. Everywhere else is that much more red.

Moreover:

For years, this continues: Urban and rural counties jostling with a small pool of counties which go back and forth every couple of elections. There's no real realignment, just a constant tug of war as the nation grows further divided.

Now, if density and diversity favour the Democratic Party, has the US got more or less densely populated and diverse since, say 1994? Especially compared to, say 1932-1993? Even since 1984? And how has the Republican Party done in House of Representatives seats in that time, worse or better?

One sees the little problem: identify that density and diversity favour the Democrats, note that the US is becoming more densely populated and diverse, and conclude the Republicans are on a long-term losing wicket. Dave Troy warns so, in his original post:

Red state values are simply incompatible with density.
...
Only subsidized suburban housing and fuel prices are insulating the United States from this global trend, and even with these artificial bulwarks, there is no good reason to think that America’s future lies in low-density development. 

Density is efficient. Density produces maximum economic output. An America that is not built fundamentally on density and efficiency is not competitive or sustainable. And a Republican party that requires America to grow inefficiently will become extinct. 

While the Republican party is retooling in the desert, it should carefully consider whether its primary issue is identity politics or whether its platform is simply not compatible with the global urban future. If that’s the case, an Hispanic candidate running on the same old Republican platform will simply not resonate. The Republican party must develop a city-friendly platform to survive. 

Cities are the future and we need candidates from both parties that understand that reality.

OK, so he is warning about the future, rather than simply consigning the Republican Party to long-term loser status. Still, there is a paradox here: density and diversity favour the Democrats according to a rural Republican v urban Democrat division which has been becoming more and more entrenched since 1984 in a US that has been becoming more diverse and more densely populated, yet the Republican Party has been having its most electorally successful period in close to 90 years. 

Yes, there are some (re)districting issues, but that does not get you very far at all in explaining the apparently contradictory pattern of "hostile" demographics yet Republican electoral success.

I would suggest a more basic issue: in a two-Party system, both Parties are effectively coalitions of interests and groups. In a highly competitive two-Party system, they are dynamic coalitions. Even with a rural-urban divide, there is nothing magical about 800 people per square mile. Push the "crossover" number up a bit to, say, 850 people per square mile, and the Republican vote goes up significantly. Push it down to, say 750 people per square mile, and the Democratic vote goes up significantly. 

So, if Republicans soft-pedal cultural issues which are working against them and start talking about poverty, equal pay, income inequality and black disadvantage (their Senate majority now includes South Carolina's first black Senator since Reconstruction), then the cross-over point can shift--in their favour. [The Republicans made gains in all demographic groups.] That is how two-Party systems work, in genuinely competitive environments.

Yes, of course demographic changes are of interest--but they are of interest in how electoral contests will be framed, not (in genuinely competitive systems) as permanent predictors of winners. Which, if that is the point Troy was trying to make, is a good one. But don't buy into "Party X is doomed because [insert demographic trend here]". It is simply not how competitive two-Party systems work.

Oh, and what does the Party of an unpopular President doing madly in second term midterms tell you about the prospects for 2016? Essentially, nothing.

[Cross-posted at Skepticlawyer.]