What's a tell-tale sign of a recession, and conversely, an indicator investors/readers should monitor to spot when the recovery has started? Retail sales -- particularly at department stores.

Most retailers will report March 2008 same-store sales this week, and Wall Street is bracing for the worst. In January 2008 and February 2008, same-store sales declined at nearly every major department store, including JC Penney (NYSE: JCP), Macy's (NYSE: M), Kohl's (NYSE: KSS), Dillard's (NYSE: DDS) and Nordstrom (NYSE: JWN).

Further, investors should watch Nordstrom's same-store sales carefully. The reason? Upscale retailer Nordstrom is a type of quick-reference, or an economic-barometer-in-a-snapshot, of the depth of a recession. If retail sales decline at broader-demographic retailers for several consecutive months, that points to a recession. But if sales decline at upscale retailer Nordstrom, that's a sign that even those with higher incomes and substantial assets are cutting back, which is a bad sign for the economy.

Nordtstrom's customers include professionals, executives and business owners -- including people who make hiring decisions. If they're cutting back, that may indicate they will not be hiring in the period ahead, which is never good news for the economy. Invariably, it means the recession's end is not near.

In Q4 2007, Nordstrom's sales fell 4.4% and earnings per share fell for the first time in more than five years to 92 cents per share. If Nordstrom's same-store sales decline again in March, that's a sign of continued belt-tightening by upper-middle and upper-income adults, and a sign that an economic recovery is not near.