The largest human migration in history is under way in East Asia. Hundreds of millions of Chinese citizens are packing their belongings and moving from the rural interior to the urban coast in search of wealth and opportunity.

Savvy investors on a similar search have taken note. In this, the third in a series on international investment, we look at two companies positioned to benefit handsomely from this migration.

The process of industrialization
The migration from rural to urban populations defines modern, industrial economies. It progresses until 80% of the population lives in urban areas, at which point the country is said to be developed.

As you can see from the chart below, China still has a way to go in this regard. Although its urban population increased from 12% in 1950 to almost 50% in 2010, 400 million Chinese citizens must still relocate before it joins the ranks of developed countries. That's the equivalent of having every U.S. citizen move to Canada!

Editorial

Source: United Nations, Department of Economic & Social Affairs (future population percentages are estimates and therefore subject to change).

Two important trends
As labor is drawn away from rural areas, farmers compensate by substituting capital. They buy tractors to plow their fields, swathers to cut their hay, and front-loaders to do their heavy-lifting.

Alternatively, as labor is drawn toward urban areas, the demand for infrastructure increases. Cities build roads, bridges, sewage systems, and buildings to serve their new residents, all of which are similarly capital-intensive.

Here's the rub
Heavy equipment manufacturers Deere (NYSE: DE) and Caterpillar (NYSE: CAT) are both positioning themselves to benefit from these trends.

Like many American companies, Deere and Caterpillar have seen their international sales increase in recent years. Deere's rose by 14% in 2010, accounting for a third of its revenue. And Caterpillar's jumped by a whopping 29%, going from $10.4 billion in 2009 to $13.4 billion in 2010.

Although this growth came largely from Central and South America, both companies now aim to benefit from demographic trends in China specifically, and emerging economies more generally. Deere introduced a line of Indian-built midsize-tractors to target customers in the developing world, announced plans for a construction-equipment factory in China, and opened a manufacturing and parts complex in Russia. And Caterpillar is expanding its operations in China, building a large engine manufacturing facility and a new 97,000 square-foot logistics center. It's also expanding its excavator manufacturing operations there by 400%.

Better yet, these companies won't cost you any sleep at night. Both have solid balance sheets, good cash flows, and responsible management teams. And both have consistently paid and increased their dividends for the last 30 years.

The bottom line
Although I advocate gaining exposure to emerging markets, you shouldn't assume an inordinate amount of risk to do so. Fortunately, by investing in strong multinational corporations like Deere and Caterpillar, you can have your cake and eat it, too.

If you're looking for more ways to expose your portfolio to growth in the emerging markets, try a free 30-day subscription to Global Gains, our Foolish newsletter focused on uncovering the world's greatest stocks.