by , 1:15 PM EDT, August 28th, 2008

The locations of Apple's U.S. retail stores closely track the U.S. Census Bureau for the highest density population centers, according to ifoAppleStoreon Thursday. However, there are a few notable exceptions.

"Apple claims that over 90 percent of the country's population is within 15 minutes of an Apple retail store, and a population analysis seems to confirm their statement," according to ifoAppleStore, a site that closely watches Apple's retail store activity.

However, there remains some notable exceptions: "Spokane (WA); Boise (ID); the eastern seaboard of Florida north of Miami; a large area of eastern Pennsylvania, Delaware and New Jersey; metro Cleveland; areas of Massachusetts and Rhode Island; and a corridor from central North Carolina south to Atlanta and Alabama."

Apple also looks at the overall wealth of the zip code and other factors when making a decision about store locations. That could explain the delay in the launch of certain locations in Idaho, North Carolina, and Alabama.

ifoAppleStore's map is large, easy to read, and offers an illuminating view of Apple's store location strategy. It may also explain why an Apple store isn't coming to your city any time soon.