Show me a young conservative and I'll show you someone with no heart. Show me an old liberal and I'll show you someone with no brains.The above quote is often (and mistakenly) attributed to Winston Churchill. Regardless of its actual origin, it is certainly widely believed.
It is, however, quite wrong, at least in the U.S, as Andrew Gelman reminds us. As the graph below shows, the most liberal age groups of American voters are the youngest and the oldest. The most conservative are the folks in their forties -- those who came of age seeing Jimmy Carter and Ronald Reagan in the White House.