1938: A difference in handling

These two letters were sent from Solingen (in Germany near Dusseldorf) to the same address (Althanstrasse 6/6) in Vienna, yet were handled differently. Why? The first is dated 9 April 1938; it arrived in Vienna the next day as shown by the indistinct Telegraph Office cancel on the back [illustrated left], and the red 68 on the front which matches the 9 WIEN 68 cancels on the back. Office 68 is at Franz Josef Bahnhof - indeed Althanstrasse passes its front door! The 10th of April, when this letter arrived, was a Sunday.

The second is dated 2 Sep 1938, and arrived in Vienna the next day. On the back is a very faint cancel, possibly the Telegraph Office (the counter letter is 'R/a'), a 1 WIEN 1 cancel, and a doubly-struck 9/4 WIEN 69 pneumatic cancel (counter letter 'R') [illustrated at left] matching the red 69 on the front. Office 69 is at Ayrenhofgasse 4, a couple of streets from Althanstrasse. The 3rd of September 1938 was a Saturday.

Why were the letters routed differently? Both offices were in service for all of 1938. The most likely explanation is that Office 69 was a local office and closed on Sundays, so the April letter, being express and (most unusually) franked with the extra 10Rpf pneumatic surcharge and with 'Durch Eilbote Zustellen' in handwriting, had to be sent to Office 68 for immediate delivery instead of waiting until Monday. A second explanation is that on 10th April 1938 the postal staff had other priorities: it was Plebiscite Day!