For dinner tonight, pick up some sushi and salad  at Walgreens. Or maybe some Target chicken.

Reflecting a major shift in the way Americans shop for food, retailers better known for selling clothes or aspirin, including Walgreens, CVS/Pharmacy and Target, are expanding in a big way into the grocery business, with fresh produce, frozen meats and, yes, even sushi.

Target invested $500 million last year alone in a new push on groceries, retrofitting some of its general merchandise stores with full-blown food sections. Sales and traffic at stores with the new grocery areas are about 6 percent higher than at similar stores without them, the company says.

Walgreens began making over some stores in Chicago and New York a year ago, and added up to 500 food items. CVS/Pharmacy last year redesigned about 200 of its stores in urban areas like Boston, Detroit and New York, and expects to make over about 20 percent of its 7,100 stores in all.

As a result, people who typically went to the grocery store once a week to stock up are instead stopping by places whose food items used to be limited to a bag of chips or a can of soup. And retailers are viewing it as an opportunity to increase sales by getting people in their stores more frequently.