The NPR station in Portland is 91.5 FM, which also happens to be the same station for NPR in Phoenix. So I wondered, what are the odds.
It looks like there are stations between 87.7 and 107.9 and each station ends in an odd number (e.g., 94.3, 106.1, etc). If you count all of them up, that makes 102 possible FM stations. So if my math is correct, that means that the odds of having the same radio frequency for the NPR station in two different cities is 1/102 or 0.98%.
You may have heard the phrase, “come on down to the left end of the dial” on NPR. This not only refers to their politics, but actually literally refers to their location: in all markets, NPR tries to secure the lowest frequencies possible. In Phx, they also have the public KBAQ, at 89.5. In any US city, you can start scanning at the left and get NPR in a few seconds. So odds are really closer to 1 in 8 or so.