SAN FRANCISCO — The United States is the biggest market for PCs in the world, but its importance is declining fast.

PC giant Dell says most of its opportunity for expansion is outside the country where it's based. "I wouldn't be surprised if the U.S. is our slowest-growing region for the next couple of quarters," CEO Michael Dell said during a recent call with Wall Street analysts.

That's likely to be true across the industry. Last year, about 70 million PCs were sold in the USA, making up about 26 percent of the worldwide market, says researcher IDC. But that's down from 35 percent five years ago, IDC says.

PC sales are growing in the USA, but not nearly as fast as in the rest of the world, says IDC tech analyst Richard Shim. That's forcing computer makers to change the way they do business, and place new emphasis on sales elsewhere, he says.

Dell wants to expand far beyond its core market of American businesses, and it is pushing hard into Brazil, Russia, India and China, and other nations. But, "Dell has always done best in English-speaking countries," said tech analyst Martin Reynolds with researcher Gartner.

That's hurt growth. Dell shares are down 7 percent since the company issued a lower-than-expected earnings report on Feb. 29.