The availability tool, which appears on Apple's website in times of scarcity, was last seen in the summer of 2008, when demand for the iPhone 3G was heavy and supplies short.
When it reappeared on Friday, only 29 of Apple's 257 stores were displaying shortages of any iPhones, according to IFOAppleStore, a website that keeps close tabs of Apple's retail business.
By Sunday morning, however, there were red "sold out" lights for selected 3GS models in all but six states.
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Kentucky's only store, in Louisville, was completely out of stock.
This year's model of the widget is considerably more accurate than the original. Last year, availability numbers were updated at the end of each business day. This year, according to IFOAppleStore, the page is linked directly to Apple's internal point-of-sale computers, allowing hourly updates for each store.
The shortages are all over the lot, but Apple seems to be having a particularly hard time meeting demand for the entry-level white iPhone 3GS. In Texas, the 16GB model is sold out in all but three of the state's 15 Apple Stores. It's not clear whether demand for that model is unusually high or if Apple just isn't making enough of them.
To check availability in the Apple Store nearest you, click here.
AT&T (t) has had 3GS supply problems from Day 1, but the widget doesn't cover their stores.
According to Apple, the older 8GB iPhone 3G is available in all its stores.