In today's world, most companies span several regions and sell across the world. As Foolish colleague Morgan Housel notes, 10 years ago, less than a third of S&P 500 revenue came from abroad. Today, that makes up more than half of the S&P 500's growth.

And that number is growing. The truth is, investors regularly underestimate how much demand comes from abroad. More importantly, for large, multinational corporations that have already established a presence in their home markets, much of their future growth comes from abroad.

With that in mind, today we're looking at Amazon.com (Nasdaq: AMZN). We'll examine not only where its sales and earnings come from, but also how its sales abroad have changed over time.

Where Amazon's sales were five years ago
Five years ago, Amazon collected 55% of its sales from the United States, while foreign markets kicked in  remaining 45%.  

Source: S&P Capital IQ.

Where Amazon's sales are today
Today, the situation hasn't changed ... at all. America still kicks in 55% of Amazon's total sales.  

However, these figures hide the incredible growth Amazon has seen both the United States and abroad.

Region 5-Year Total Sales Growth
United States 297%
International 310%

Source: S&P Capital IQ.

It's not that Amazon hasn't been doing impressively internationally that's keeping its international sales at the same level while other American companies see a growing percentage of sales abroad; it's that Amazon is also executing so exceptionally in America. Another key factor in Amazon's success is that it saw the international opportunity and expanded so aggressively in its infancy.

In most of Amazon's markets, it already enjoys market leadership. Of the International markets Amazon has expanded to -- Germany, the United Kingdom, France, Japan, Italy, Canada, and China -- one country presents not only the largest challenge, but the greatest opportunity.

Of course, I'm talking about China. Amazon purchased Joyo.com in 2004 for $75 million and has been ramping its Chinese operations up since. While Amazon doesn't disclose foreign sales by country, estimates placed China at 8.6% of Amazon's foreign sales in 2009, which is only about 4% of companywide sales.

However, the future opportunity of e-commerce in China is something that can't be overlooked. The country is home to an underdeveloped conventional retail sector but has nearly 500 million Internet users who have grown up with the idea of the Internet as a means of commerce. These lucrative dynamics could have China leapfrogging the United States as the largest e-commerce market in the world by 2015.

Amazon faces plenty of completion from a whole host of rivals, including E-Commerce Dangdang (NYSE: DANG) and Chinese selling site Taobao -- which is building out a new e-commerce platform -- so success isn't assured. However, with its expertise and vast resources, Amazon could be at the forefront of a massive market opportunity.

Competitor checkup
One last point to check is how Amazon's footprint compares with some of its Internet peers and industry rivals.

Company

Geography With Most Sales

Percent of Sales

Amazon United States 55%
eBay (Nasdaq: EBAY) United States 46%
Wal-Mart (NYSE: WMT) United States 72%*
Mercadolibre (Nasdaq: MELI) Brazil 57%

Source: S&P Capital IQ.
*Includes author estimates for Sam's Club sales.

Relative to its largest peer, Wal-Mart, Amazon has a strong International reach. However, like Amazon, Wal-Mart is also making an international push.

The inclusion of Mercadolibre brings up an interesting point -- Amazon's lack of presence in Latin America. Many other commerce and Internet companies have moved to South America and have seen strong growth rates in the region. Without further expansion, Amazon isn't set to benefit from the region's growth.

Keep searching
If you're looking to stay updated on Amazon or any other companies listed above, make sure to add them to our free watchlist service, My Watchlist. It's free, and it helps you constantly stay updated on news and analysis on your favorite companies.

Eric Bleeker owns shares of no companies listed above. You can follow him on Twitter to see all of his technology and market commentary. The Motley Fool owns shares of Wal-Mart Stores. Motley Fool newsletter services have recommended buying shares of eBay, Amazon.com, Mercadolibre, and Wal-Mart Stores and creating a diagonal call position in Wal-Mart Stores. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.