According to Baseline, Inc., a company owned by the New York Times that tracks television and film industry data, the median age of viewers of the Big Four broadcast networks–NBC, ABC, CBS, and Fox–is 51. Baseline says the audience has aged at twice the rate of the general population, and that younger viewers have defected to cable and the web.

In the first place: duh. Most of us over 50 remember when our TV choices were limited to the above networks excluding Fox, maybe with the addition of a local PBS affiliate and, if we lived in a really big market, an independent station or two. (Kids: ask your parents about the shadowy netherworld called “UHF.”) People go with what they know, and we know the big networks. No surprise there.

(For the record, I rarely watch the Big Four. I almost never watch network news, and I can think of only one network series–Friday Night Lights–that I’ve watched religiously over the last four years.)

So what can marketers take from this fact?

First, remember that the “median” is the middle value: half the viewers are above that line and half are below. It means that the audience for the Big Four trends older than, say, the audience for video games. But half of the audience is still under 51. You can’t discount the Big Four as a way to reach your desirable younger audience.

Second, remember that your “desirable younger audience” might not be as desirable as you think. The wealth in America is still concentrated among Baby Boomers. Although Boomers have taken a big hit in the wealth department recently, they’re still the people with the money. People over 50 have more money, and more money to spend, and television is still an excellent way to reach them.

Third, don’t take this to mean that older American’s aren’t using the Internet in general and social networks in particular. The average age of Facebook users is 38.4, and getting higher. The average age of LinkedIn users is 44.3.

Finally, it’s also interesting to note that the money is online: according to PewInternet, 94% of Americans who make more than $75,000 a year are online.

“Big Four” TV is still a great way to reach the people in America with all the money. And asking them to see you online is a great way to engage them and help them make smart purchase decisions. If you think your audience isn’t watching TV or isn’t going to the web, you’re wrong: in most cases, it’s doing both.