What is the pattern behind this list of US cities? Really quite simple for US folk, and I think most educated foreigners have the requisite background info.

US City US State
Añasco PR
Carolina PR
Nantucket MA
Newland NC
Portage IN
Plano TX

A friend of mine made the following image, which is pretty but not necessarily helpful! map of Eastern USA (Table as image)

  • 3
    $\begingroup$ This is diabolical! I've come up with what I thought were 2 good leads, but they haven't taken me anywhere: 1: it looks like rot13(n Svobanppv frdhrapr jurer gurer vf ab erfhyg sbe bar, ohg gjb, guerr naq svir fbzrubj rdhngr gb Arjynaq, Cbegntr naq Cynab). and 2: rot13(gur bayl fgngr jvgu nyy guerr pvgvrf vf Vaqvnan) $\endgroup$
    – Stevish
    Dec 8, 2023 at 15:07
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    $\begingroup$ All I is that the states are progressing westward on the map and the places within them are progressing alphabetically $\endgroup$
    – PDT
    Dec 10, 2023 at 7:38
  • 1
    $\begingroup$ The west to east property is a consequence of the underlying pattern, I think $\endgroup$
    – Laska
    Dec 10, 2023 at 8:03

1 Answer 1


This puzzle combines two things:

ZIP codes (postal codes used in the U.S.) and Fibonacci numbers.

The title: none, none, Newland, Portage, Plano

ZIP codes use a five-digit format. There are five Fibonacci numbers with five digits: 10946, 17711, 28657, 46368 and 75025. The first two numbers are not valid ZIP codes (or at least not valid ZIP codes assigned to locations), but the next three numbers are the ZIP code of Newland, North Carolina; the ZIP code of Portage, Indiana and one of the ZIP codes assigned to Plano, Texas.

The table: Añasco, Carolina, Nantucket

ZIP codes may have leading zeros, which yields three more numbers that are both Fibonacci numbers and valid ZIP codes: 00610 for Añasco, Puerto Rico; 00987 for parts of Carolina, Puerto Rico and 02584 for parts of Nantucket, Massachusetts.

  • $\begingroup$ Perfect! This captures it all! The title, with the duplicate first term was intended to “suggest” Fibonacci $\endgroup$
    – Laska
    Dec 11, 2023 at 13:36

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