This is what happens when workers' wages fall...

...they quit buying things in stores.

Here's a chart that shows how median household income has fallen since 2000:

American households are dying a slow financial death. Median household income fell $4,500 since 2008, from $56,000 to $51,500.

That means retail chains aren't selling as much as they expected -- by the biggest margins in 13 years, according to Bloomberg:

Most retail segments are showing profit declines, with department stores, teen-apparel chains and home-furnishing stores faring the worst, Retail Metrics said. About 41 percent of retailers have missed estimates, while 45 percent have beat. 

Improved weather, pent-up demand and better employment trends may help the industry in the second quarter (Ken) Perkins (Retail Metrics’ president) said. Analysts are projecting an 8.6 percent gain in profit for the current three-month period, he said.

That may be optimistic, since most of the jobs being created only pay low wages.