In today's world, most companies span several regions and sell around the world. As Foolish colleague Morgan Housel notes, 10 years ago, less than a third of S&P 500 revenue growth came from abroad. Today, that area makes up 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 ExxonMobil (NYSE: XOM). We'll examine not only where its sales and earnings come from, but also how its sales abroad have changed over time.

Where ExxonMobil's sales were four years ago
Four years ago, ExxonMobil produced 30% of its sales in the United States, but like most oil majors, it had a well-diversified geographic presence.

Source: S&P Capital IQ.

Where ExxonMobil's sales are today
Today, the trend in Exxon's business is little changed from four years ago.

Source: S&P Capital IQ.

That's not to say there hasn't been any activity involving Exxon's sales to other geographies. In 2009, its sales to the United States slipped below 30%, but the company pulled off a major $41 billion deal to buy XTO Energy, a domestic supplier of natural gas. That helped push Exxon's sales to America back up.

However, with the oil majors, it's important to see where the assets they have are. Selling to different markets can be important, but getting a feel for the potential for future growth and political risk where companies are drilling is more important. This reality was highlighted last week, when Chevron (NYSE: CVX) and drilling contractor Transocean (NYSE: RIG) started feeling the heat from the Brazilian government. The country, which politically is much more stable than many other markets -- like Nigeria,  for one -- is seeking an $11 billion civil lawsuit against the pair for an oil spill that leaked bout 3,000 barrels into the ocean, which is a mere fraction of the 4.9 billion that gushed into the Gulf last year.

So, let's take a look at where Exxon's assets are congregated.

Source: S&P Capital IQ. Exxon also has another 3% of assets in Norway that are unlisted in the chart.

While Exxon has assets in some areas with a high potential for political risk, including Angola and Nigeria, overall, the majority of its assets remain in the United States and Canada. Compare that with Chevron, which has 27% of its upstream operations internationally and splits downstream close to 50/50 between the United States and other geographies. ConocoPhillips (NYSE: COP) is pretty similar to Exxon in terms of where its assets are located, with 58% of its assets in the U.S. and Canada.

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Eric Bleeker owns shares of no companies listed above. The Motley Fool owns shares of Transocean. Motley Fool newsletter services have recommended buying shares of Chevron and ExxonMobil.

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