Close your eyes ...

Imagine yourself as an investor more than a century ago -- prior to the industrialization of the United States. Would you have bet your money on the growth potential of our nation? Knowing the outcome a hundred years later, you wouldn't hesitate to answer.

We can't rewind to the past
Unfortunately for our generation, those days are long gone on domestic soil. The opportunity for high-flying GDP growth and rapid infrastructure development is in the past.

GDP growth in the United States has averaged just 3.3% annually for the past 25 years. It will struggle to reach even 1% this year, despite continuous technological advancement in the United States. And because many guru investors, including Warren Buffett, argue that GDP growth is a key ingredient to long-term market returns, the future doesn't look so bright for domestic-only investors.

But even if you weren't around for the roaring '20s, you didn't completely miss your chance for the exponential growth that infrastructure development can offer. While the U.S. can no longer capitalize on heavy infrastructure expansion for growth, beyond our borders lies a world full of nations -- exploding with growth -- that can.

A new investment frontier
China and India certainly won't be running out of steam soon, but these countries are already emerging and are off to a great start. To capture the even more exciting early years of initial growth, you need to find economies that possess characteristics that point toward becoming the next emerging market.

While not as prominent as the BRIC foursome of Brazil, Russia, India, and China, investor buzz is starting to collect around tiny economies such as Vietnam, Indonesia, and Bulgaria. Dubbed as the "Frontier Markets" by the Barra Index, these economies are just beginning their development stages; they hold less than 1% of the money invested in stock markets worldwide.

But that will all change soon. Goldman Sachs anticipates that Indonesia and Vietnam will be two of the 15 largest economies. And looking at the accomplishments of past emerging markets, the prospects are enticing. According to a recent Newsweek article, the current major emerging markets, including China and India, also held fewer than 1% of worldwide stock market money back in 1987. Today, that share has increased to 12%.

Sign me up
Unfortunately, gaining access to these markets isn't always that easy. While a handful of notable American Depositary Receipts (ADRs), such as Telkom Indonesia (NYSE: TLK) or Bancolombia (NYSE: CIB), offer investors direct exposure to these frontier economies, there aren't many companies available for direct investment. But that doesn't mean your only option is to fall back on an ETF or closed-end fund.

The key is to search for strong global players that can capitalize on the growth in these countries by investing portions of their business there. This will provide exposure while minimizing some of the risk inherent in investing in frontier markets.

For example, American International Group (NYSE: AIG) owns a majority stake in a Bulgarian telecommunications company, and Allied Irish Banks (NYSE: AIB) agreed to purchase a stake in a Bulgarian bank earlier this year. General Electric (NYSE: GE) has been investing in Vietnam since 1993, and energy behemoth ConocoPhillips (NYSE: COP) has become the largest foreign investor in any industry in Vietnam -- plowing more than $1.3 billion into invested capital projects since 1996. And while you probably associate Nigeria with scam emails, it's the largest oil producer in Africa. ExxonMobil (NYSE: XOM) is so bullish on the country's prospects that it will continue its $11 billion investment in the country's oil sector through 2011.

And it isn't just enormous firms who are optimistic. Fund managers are tapping into these countries for foreign portfolio exposure. According to Cliff Quisenberry, manager of the Eaton Vance Tax Managed Emerging Markets Fund, countries in the bottom 4% of the world capitalization universe returned roughly 18.1% annualized over the past decade, versus a 5.6% average return for developed markets.

Don't miss your chance this time
A recent U.N. conference had good reason to rank Vietnam as the sixth most desirable place to invest. Simply put, frontier markets offer untapped potential to informed investors.

That's why our Motley Fool Global Gains team is headed to some of these markets (Indonesia, Vietnam, and Singapore, as well as China) in a few weeks for a firsthand look at the growth opportunities in these regions.

Come along with us by signing up for our team's free dispatches from the road. All you have to do is enter your email address in the box below.