Mistermix at Balloon Juice posted this poll showing the ideological spectrum of American adults from "Very Conservative" to "Very Liberal" and, naturally, there aren't many people who self-identify as "Liberal" or "Very Liberal".
Don't believe the results.
As I've written before, the word "Liberal" has been stigmatized for more than 50 years. In the general population, referring to yourself as liberal is almost like referring to yourself as an anti-American baby killer. Far-right activists have successfully demonized the word.
What do these words mean to regular people? Do people really understand what they are? If a guy is frugal with money, hates to pay taxes and doesn't particularly care for the government, but, at the same time, he voted for Barack Obama, he's pro-choice and anti-war, what is he?
And finally, if you go through issue polls, one by one, you'll find that most Americans generally fall into the "Liberal" category. We're pro-choice (though the abortion labels are misleading, too), pro-same-sex marriage, pro-gun control, pro-healthcare reform, pro-Social Security and Medicare, etc, etc.
But none of this matters because politicians look at these self-identification polls and govern accordingly. And they're "Very Wrong" to do so.