For years, there have been two sides to the grocery wars: traditional stores, offering the convenience of last-minute stock-ups (so long as you don't mind lines and crowds), and online delivery services, offering the ease of at-home shopping (so long as you live in or near a major city).
But with so much at stake in the $1 trillion U.S. grocery industry, a hybrid model is emerging that may challenge both: pickup, or ordering items online and collecting them at a nearby depot. The practice is already popular overseas, thanks to distributors like Tesco. Now U.S. chains like Whole Foods and...