While other retail chains stumbled as the current recession dug in, Wal-Mart continued to report strong sales numbers. Its performance made sense -- when times get tight, price does make a difference, and love Wal-Mart or hate it, you can't deny that the company features low prices.

But no longer: The lead story on both the Wall Street Journal and Financial Times' Web sites on Thursday morning tell us that Wal-Mart is also beginning to hurt. According to the Financial Times, Wal-Mart reported "that fourth quarter sales were below expectations and that it would downgrade its earnings forecast."

What does that really mean? You can get a deliciously visceral sense of just what kind of role Wal-Mart has played in the U.S. economy over the last quarter-century from a nifty data-visualization gizmo produced by FlowingData that documents the spread of new Wal-Mart stores across the country, year-by-year. (Thanks to Felix Salmon for the link.)

(I originally embedded the data-visualization doohicky in this post, but deleted it after reports that browsers were crashing. You can find it )