Limited Importance of American Elections

I've spent a considerable amount on time on this blog describing the reasons why I and others vote, even though the expected value of the vote is close to zero. What I haven't discussed, is how important the outcome of those election actually are. According to The Economist, not that important:

But I think you'll also find that policy doesn't swing very wildly when government changes hands. Parties do what they can to reward supporters, but they can't do too much. Many interest groups play both sides, exerting significant influence on policy regardless of the party in power. Military suppliers, big Wall Street interests, and the economic middle-class may do better or worse, but they always do pretty well. Moreover, policy is quite constrained by general public opinion. Neither party will drift too far from the median voter.

Certainly there is a marginal value to each vote and to each election, but it's probably much less than the pundits and politicians would have us believe.