While "156603" may look like a standard U.S. ZIP code, it actually represents a mysterious "ghost" in the postal system. In the United States, ZIP codes are five digits long; "156603" is a , making it an invalid code for standard mail delivery within the U.S..
: The letter arrives at a massive sorting facility. High-speed scanners whir, reading thousands of envelopes a minute. When it hits "156603," the machine pauses. The extra digit confuses the logic—is it a typo for Topeka, Kansas (66603) or perhaps a military address at FPO AP (96603)?. 156603 zip
: Unable to find a home, the letter is tossed into a "Nixie" bin for manual review. A postal worker looks at the six digits. They know that Poughkeepsie, New York , stops at 12603 and Oakland, California , only goes up to 94603. While "156603" may look like a standard U