Facebook recently released a report that revealed only 30% of the Website's 400 million users are within the United States.
A few highlights from the data:
The demographics show, among other results, the percentage of Facebook users identifying themselves as 'female' is higher than the percentage of women that make up the population of the United States.
The infographic also highlights the top US cities on Facebook. The top 10 cities with the largest populations on Facebook are (from greatest to least): New York City, Los Angeles, Chicago, Houston, Phoenix, Philadelphia, Dallas, San Diego, San Jose, and San Antonio.
Interestingly, a far greater proportion of the US Facebook population declines to list their political beliefs (or lists them as "other") than the total US population.