Department stores are the only group of retailers that lost money in Q2 and there’s no end in sight.

That’s according to research firm Retail Metrics’ Retail Headwinds Persist report, which examines an index of 116 chains, RetailDive reports. But you can’t blame all of department stores’ woes on Amazon—the shifting landscape of American wealth is also having a huge impact.

“Often left unsaid, and in our opinion underestimated, in terms of retailers’ struggles has been the long, slow steady erosion of the American middle class,” says Retail Metrics founder Ken Perkins. “A large vibrant middle class fueled economic growth and consumption for much of the post-war period.”

Perkins cites Pew Research Center data showing the steady erosion of the American middle class since 1971, making it harder for many Americans to spend as much as they historically have on retail. [RD]