Apple’s two largest New York City retail stores are now known to be some of the town’s largest retail cash cows, with the 5th Avenue flagship alone having drawn in $440 million in one year.

Part of this may be attributable to people shopping less in the SoHo area, instead purchasing more goods at Fifth Avenue stores. Such behavior would be odd however, considering that Fifth Avenue stores typically have shorter hours than their SoHo counterparts. The Fifth Avenue Apple Store pulls in at least some extra revenue as a result of being open 24 hours a day.

By comparison, the slightly larger store at Prince and Green Street generates $100 million. Other shops on Fifth Avenue are generating still lower profits, such as Zara Clothing, which brings in about $25 million a year.

Combined with the continuing increases in foot traffic from year-to-year at Apple’s stores, word of such massive amounts of revenue leaves little surprise as to why the company is vowing large-scale makeovers of its existing stores and still plans to add 25 stores in fiscal 2009 at a time when established electronics chains have folded or put a freeze on expansion. Additional, optimized retail space has to date quickly translated into more customers, particularly in those areas where no official stores had existed before.

To that extent, Apple has already said that roughly half of the 25 new stores planned for fiscal 2009 are intended for non-US locations. Unofficially, these are known to include multiple first stores in major but previously unserved cities.