New York-based computer developer Mike Linden, 27, cannot remember the last time he stepped into a big department store.

From diapers to groceries and meals delivered along with a recipe to his door, his three-person household buys almost everything online.

Several big retailers such as department stores Macy's and JC Penney are struggling to survive in the new environment of online sales and hip physical stores.

Macy's still has 43 million people shopping at its stores each year. But in March, it reported its eighth quarterly decline in sales in a row - and announced plans to close 68 of its stores nationwide.

"Macy's had too many stores to start with, it's a miracle they kept it going as long as they did," said Ms Paula Rosenblum, co-founder and managing partner at Miami-based Retail Systems Research.

As for JC Penney, its customers are "ageing out", she said. It plans to close 138 stores starting from July 31.