The famous “47 million uninsured” is made up almost entirely of people who actually are covered, or who are CHOOSING not to be:

http://butnowyouknow.wordpress.com/2009/08/05/who-are-the-47-million-uninsured/

The largest, overlapping, groups of uninsured in the US include:

9,000,000 Millionaires
27,000,000 people who make more than $50,000 per year, but choose not to get insurance
22,000,000 Young adults who can afford insurance, but choose not to
14,000,000 People who can already get medicaid, but choose not to
11,000,000 Illegal Immigrants
23,000,000 People who are actually insured. That’s right; you’ve been lied to…surprised?

This adds up to more than forty seven million, because of the overlap – for example young adults who are millionaires and change insurance companies fit into four categories, above.

There is a detailed breakdown of the six categories above, on the website I’ve linked, including footnotes to sources…but you don’t need those footnotes, because it’s easy enough for you to find references to all six of the categories, from any mainstream media or government sources you prefer.