WASHINGTON, March 11 (Xinhua) -- Retailers in the United States were investing both online and offline, as multichannel or even "omni-channel" shopping became more popular among their customers, according to a study released by the National Retail Federation (NRF) on Monday.

"To bolster their customers' store and digital experiences, increasingly customer-centric retailers are investing in omni-channel fulfillment services, personalization tactics and mobile marketing," said the NRF.

Although online shopping became a more popular channel for customers these days, the study found that retailers in the United States still planned to expand their physical stores.

"More than half of surveyed retailers confirm they will open stores in 2019, and 36 percent will have a higher store count than in 2018," said the NRF, "only 7 percent of respondents said their net store count would decrease."

This kind of investment was seen as the new effort of retailers who was aiming at providing better shopping experience while more consumers embrace multichannel shopping.

"Retailers are evolving with customers' shopping behaviors by creating a seamless shopping experience online and in store," said Mark Mathews, vice president of research development and industry analysis of NRF.

Besides, social marketing, an approach to develop activities aimed at changing or maintaining people's behavior, had been a new leading tactic in marketing these days.

Sucharita Kodali, vice president and principal analyst at a market research company named Forrester, said that several other types of marketing tactics were growing along with social marketing.

"Not only has social knocked search marketing from its spot as the top-growing digital marketing tactic, but retailers are also tapping into video marketing and online marketplaces as increasingly important tools for product discovery and research," said Kodali.