America Instagrams Costco, Tweets at Wal-Mart

Maybe it's the gargantuan boxes or pallets stacked to the ceiling, but Instagrammers love taking photos at Costco. Over at Wal-Mart, shoppers prefer Twitter, and Safeway shoppers check in with Yelp. All of these behaviors go by the same name — social media moments, according to LocalResponse, a mobile advertising provider. The company released its first study of retail check-ins from more than 136,500 social media moments at 10 top U.S. retailers, using four social networks — foursquare, Twitter, Yelp and Instagram — over the summer.