Voters tend to toss incumbent parties out of the White House when the economy sours

From The Rise and Fall of the Parties by Jay Cost. Political prognosticating is meager gruel. But somehow unavoidable and to some extent always alluring.

Cost has some interesting historical suggestions. He observes that, despite all the nonsensical talk about an emerging Democratic Majority, (which has to have had one of the longest stretches of emergence of all time), Republicans have, with many ebbs and flows, steadily been gaining ascendancy over the past thirty years. However,

Note that very little of this has to do with the triumph of conservatism over liberalism or vice versa. Voters tend to toss incumbent parties out of the White House when the economy sours, and prior to that point they tend to favor the opposition for the rest of the electoral offices. These forces combined to rout the GOP in 2008. It is now the Democrats’ turn to worry about their inevitable fall from grace. Maybe they can delay it past 2016, but it is coming.

The ebb and flow of party fortunes is a separate issue from the long term trends in the culture.