CC Image Courtesy of Stephen Cummings on Flickr
The Washington, D.C., area is expecting a major snow storm this weekend. All reports I've heard point to major overcrowding and supply shortages at local grocery stores ahead of the storm. The Whole Foods near Logan Circle was closed for 30 minutes because the crowds were causing fire safety concerns, reports the Washington Post.
In theory, the grocery stores don't need to be chaos before storms. When demand exceeds supply, the price level rises until enough people don't want the good at the higher price. The most price-sensitive people buy other things or wait for the price to fall. Stores could have a policy of hiking prices 20% ahead of major disaster periods, for instance. However, for political reasons and for fear of customer backlash, they may choose not to (we saw what happened with the 5 cent bag fee). If you don't really need to go shopping, you'll wait until next weekend. If your cupboards are bare, you'll be willing to pay the premium.
Instead, the scarce good that is space in the grocery store is allocated by time wasted waiting in line. Again, only those who really need groceries today will be willing to bear the lines.
Which is the better way to sort customers? Economists generally prefer the former method. If customers have to pay a premium, they might as well do so in money instead of time. At least the higher prices transfer money to the stores and the local government (via sales taxes), and the higher prices (in the long run) induce more firms to provide the scarce good. In contrast, if people have to wait in long lines, that doesn't do anyone any good and is a waste of resources.
However, both methods create a sort of economic efficiency, by getting the goods to the people who most need them, and who are willing to "pay" the most, whether it be in time or money. But note that, to some people, time is relatively more expensive than it is for others. So the final allocation won't quite be the same.