Matt Yglesias has some indicative numbers:
One month of data can be very noisy, but I think that if you look at March 2011 compared to March 2012 you can clearly see the End of Retail.
According to the BLS, about 2 million more people were working last month than were working a year ago. But we have 10,000 fewer people working in general merchandise stores. We have 20,000 fewer people working in electronics and appliance stores. We have 17,000 fewer people working in “sporting goods, hobby, book, and music stores.” Now the overall BLS retail trade category includes other stuff including things like health and personal care stores that seem healthy. But the point is that over the course of a year in which the level of economic activity has clearly risen, certain major categories of big box retail have shed jobs. Given a few months in a row of torrid overall growth, presumably some of that would stabilize. But I think you have to see this as a part of the economy that’s facing a persistent decline driven by e-commerce, a decline that should only accelerate since a ton of people are going to get their first smartphone in the next 12-18 months.