Wal-Mart stores in Arizona now stock Grand Canyon sweet onions while aisles in New York display state-grown eggplant, as the world's largest retailer says it has become the nation's largest buyer of locally grown fruits and vegetables.

Wal-Mart Stores Inc. plans to purchase and sell $400 million worth of produce grown by local farmers within its state stores this year, an effort the company says will only grow. Academic studies show buying locally cuts down on transportation mileage while also assuring customers of a product's providence amid mass recalls.

For example, the retail giant once only bought peaches from a few suppliers. Now, Wal-Mart buys 12 million pounds of peaches annually from farms in 18 different states, she said.

Because of that, the company estimates it saves about 100,000 gallons of diesel fuel a year and cuts away 672,000 food miles -- the distance produce travels from farm to a customer's plate. That adds up to $1.4 million in annual savings, Galberth said.

"It's one of the ways we've been able to keep costs down," Galberth said. "Our customers right now are struggling with tough economic times and looking to us to provide them with products that are at the quality they want and a price they can afford."