Mexico (1945) Cover / Union Hidalgo to Skive (Denmark) – Postmark Error

**1945 Mexico to Denmark – Commercial Airmail Cover with Mechanical Date-Wheel Shift Error**

A fascinating and highly unusual international commercial airmail cover sent from the provincial office of **Unión Hidalgo (Oaxaca, Mexico)** to **Skive (Denmark)**, documenting a spectacular and mathematically proven **mechanical dial-shift error** by the local postal clerk.

* **The Mechanical Date Shift Rarity:** The obverse displays the circular town departure datestamp of **Unión Hidalgo** showing the impossible date of **28/11/1934** (as the stamps were not issued until 1945). The reverse side holds the official **”Servicio Aéreo”** (Airmail Service) transit datestamp cleanly applied on **28/12/1945**, confirming an 11-day domestic transit from Oaxaca to Mexico City.
* **Postal Mechanics Analysis:** Comparative research definitively proves that the actual mailing date was **17/12/1945**. During the daily manual setting of the steel-wheel canceller, the postal clerk accidentally misaligned the inner mechanism, shifting every single metal digit cylinder exactly one positional unit out of place. This mechanical failure systematically transformed **17/12/1945** into **28/11/1934** across the year, month, and day wheels.