It all started innocently enough. "Write an article about international investing for the Fool's 15th Anniversary," our editor asked. "Something about how more Americans should be doing it and that it's easier than ever before thanks to ETFs and the like."

These were fair points (and it's always better to stay on an editor's good side), so I fired up LexisNexis to get a better feeling for just how easy it was to invest abroad way back in 1993 when The Motley Fool was founded. I expected to read about some kind of byzantine regulations that prevented Americans from diversifying globally.

Instead, I found a lot of articles that sounded like they were written in 2008, which means that as investors, we still aren't investing enough in foreign markets.

Let's go to the videotape
As it turns out, investing abroad in 1993 wasn't all that hard. There were a wide variety of mutual funds and ADRs for you to buy, and there were lots of folks telling you to buy them.

The media accounts of the day also reveal 1993 to have been a booming year for international investment. The New York Times wrote the following in an October column:

[Americans] discouraged by low-yielding investments at home and attracted by high returns in quick-growing overseas economies like China ... are growing increasingly bold about investing abroad -- especially in the countries that were once called third-world or underdeveloped areas but are now often referred to by funds as "emerging markets."

Heck, fund manager Helen Hayes of Janus was fortunate enough to catch onto "a Finnish company called Nokia (NYSE:NOK), very strong in the exploding international telecommunications market."

Yes, "emerging markets" was a new term, and the companies and countries it encompassed were relatively unknown. But the benefits of buying them were as plain as day back then as well.

For example, after talking with Templeton's Mark Mobius (still a well-regarded name in international investing), a Florida newspaper advised its readers that international stocks offered better performance, reduced volatility, and bigger opportunities. "The financial world is a lot more global than it used to be," it wrote, and "foreign stocks frequently zig when U.S. stocks zag."We still very much agree.

It was not all bright copper kettles and warm woolen mittens
Yet by 1997, Asia was gripped by a debt crisis that sent stocks plummeting across the region, particularly in Thailand, Malaysia, Indonesia, and the Philippines. These were also the four countries that were considered in 1993 to be Asia's Emerging Tigers, and according to Investors Chronicle, these countries, along with Hong Kong, Singapore, Taiwan, and Korea, were the places where "most emerging market funds [were] concentrated."

China and India, on the other hand -- the two countries that rank among the top emerging markets success stories of the past 15 years -- were largely afterthoughts. China was a newly opened economy that attracted a great deal of skepticism due to its communist ruling party. As a result, it wasn't tracked in any of our international stock indexes. And India's market, though it was on the radars of international investors, was only tracked by one of those three indexes.

Similarly, when it came to Latin America, Investors Chronicle advised its readers that thanks to reduced inflation, freer trade, and greater democracy, the continent would offer meaningful returns going forward. Unfortunately, it also warned readers to stay away from Brazil, which "remains a basket case." For anyone who's been following Latin America, Brazil is among the few countries that can point to sustained economic progress.

In other words, while analysts were absolutely right to be telling you to invest abroad in 1993, they did a relatively poor job of identifying the specific countries and companies that would do best.

What this means for you
We find ourselves in a remarkably similar spot today. Given the current financial crisis here and 15 years of rapid growth abroad, it's clear that the U.S. is even less the center of the financial world today than it was in 1993. As Zachary Karabell observed in The Wall Street Journal last week, "The outflow of wealth [from the U.S.] is a fact," and it is "leading the rest of the world to form bonds that bypass the U.S."

That means that, as an investor, you should expect your returns from U.S. stocks over the next 15 years to be even worse than the 6-7% annually they offered over the past 15 years. Perhaps even more frightening is that one-time U.S. stalwarts such as General Motors (NYSE:GM), Xerox (NYSE:XRX), and Ford Motor (NYSE:F) all have negative returns over the same time period. If those numbers are smaller than you were hoping for, then it's absolutely crucial -- as it was in 1993 -- to make or increase your investments abroad.

What's still not clear, however, is which specific countries and companies will do best. We have some ideas at Motley Fool Global Gains, where we're recommending our members concentrate on megatrends such as worldwide infrastructure development (Cemex (NYSE:CX)), increasing demand for energy (CNOOC (NYSE:CEO)), and the rise of the middle class in places such as China and India (Luxottica (NYSE:LUX)), but we also want our members to spread their investments around the world and to do so with a longtime horizon.

That's the only way to take advantage
See, while emerging markets are full of potential, they are also full of unknowns. That shouldn't scare you off, but should rather force you to devise strategies -- such as broad diversification -- to cope.

Because the fact of the matter is that financial advisors today are more bullish on international investments than ever before.

In 1993, for example, The New York Times reported that most advisors told their clients to stash 10% to 20% of their assets abroad. Asset manager T. Rowe Price was recommending at the time "an 80-20 split between domestic and foreign holdings in a stock portfolio."

Fast forward to today, and Ibbotson & Associates is telling clients to invest 35% of their money abroad, Citigroup recently increased its international allocation guidance to 55%, and PIMCO co-CEO Mohamed El-Erian told Money that Americans should have 66% of their investable assets in foreign stocks. In fact, being underexposed to international stocks is the biggest threat to your portfolio today.

We should all be rich by now
In 1993, we were off to a good start. Thanks to strong performance in 1992 and 1993, international mutual funds saw record inflows, and by 1994, international mutual funds managed more than $100 billion (or 6.6%) of all U.S. mutual fund assets. Yet for whatever reason -- volatility, the 1997 financial crisis, or the tech bubble that kept most Americans focused on Silicon Valley -- the trend toward greater investment abroad lost momentum. (And we were complicit: The Motley Fool didn't formally start covering foreign stocks until 2006 when we launched Global Gains.)

Yes, American investment abroad has increased over the past 15 years, but according to Investment Company Institute data, it still only represents 14% of total mutual fund industry assets. That's not near where it should be.

1993 redux
Individual investor Paul Feldman told The New York Times 15 years ago, "If you're willing to sit back and ride out the ups and downs, there's more of an upside for the emerging market economies than there is for the existing, well-established economies."

That's as true today as ever before, but the question is: Are you willing to ride out the ups and downs? Given the still low exposure of most Americans to foreign markets, most of us, it seems, are not.

Our hope today -- as we celebrate our 15th Foolish Anniversary -- is that you will be. To get started investing intelligently abroad, click here to come join us at Global Gains free for 30 days.

Tim Hanson does not own shares of any company mentioned. Cemex, CNOOC, and Luxottica are Motley Fool Global Gains recommendations. The Fool owns shares of Cemex, which is also a Stock Advisor pick. Nokia is an Inside Value choice. The Fool's disclosure policy notes that the traditional 15th anniversary gift is crystal.