Why would President Barack Obama tie up Los Angeles traffic just to fit in a personal appearance on The Tonight Show with Jay Leno on Wednesday? Angelenos don't usually host presidential candidates this late in the season. 

The answer is obvious: Demography.

Jay Leno's audience profile is very different from that of his competitors. And it's not just WHO watches Leno.... it's the way those WHOs look at the world. 

Leno's audience tends to be older (his average viewer is 58), whiter, and more concentrated (relative to his competitors) in less-urban TV markets. Leno is still number one in late night, but his show is not pulling in the profits it once did. His audience doesn't have a lot of extra cash to buy things. They tend to be interested in politics, so they're not low-information voters. But they also tend to be "framers" — they like to talk about politics by talking about personalities and characters. 

They also tend to like guests that Leno confers his blessing on. I don't want to read too much into a single appearance; after all, Leno's 4.4 million viewers a night are a captive audience in themselves, even without the demographic considerations.  But they're the RIGHT type of collective audience for Obama.