ComScore released its July 2011 U.S. smartphone data this week and as usual Asymco‘s Horace Dediu has done the best job of turning the numbers into striking — and insightful — graphics.

On Thursday he released three charts that show:

1. The scale of the opportunity for further smartphone growth
2. The extent to which Apple’s (AAPL) iPhone and Google’s (GOOG) Android are squeezing out the competition
3. The challenge Microsoft (MSFT) faces as it tries to get back into the game

I’m particularly fond of the chart at right because it gives you a sense of how large the U.S. cell phone market really is and how much room for growth it offers smartphone manufacturers.

You can see the other two charts at the Asmyco entry Dediu has titled The third smartphone ecosystem: What are the odds?

The third ecosystem, of course, is Microsoft’s Windows Phone 7, which many analysts believe could capture the lion’s share of the blue sky in the graph above.

Dediu is skeptical. He writes:

In the last 12 months, Android gained 25 million users in the US. iPhone gained 9.5 million while Blackberry lost 3.2 million and Microsoft lost 1.6 million. Other platforms had a net loss of 1.2 million.

The total net gain of smartphones was about 29 million new users.

RIM switched from being a consistent net gainer of users to a consistent net loser of users in October 2010. Windows Phone is showing signs of holding the line on user base erosion but share remains below 5% (now at 4.7% vs. 4.6% last month).

To put the mountain-sized hurdle in perspective, Android now has 7 times more users in the US while iPhone has about 5 times more. To become the largest mobile platform in the US, as some analysts are predicting, Microsoft has a 12:1 disadvantage that looks to continue to grow.

Those are some pretty tough odds.

One of the great things about Dediu’s Asymco blog, besides the eye-catching graphics, is the quality of the discussion he moderates. As of Friday morning, this post had generated 62 comments. You can add yours here.