After having been caught up with this TL for a while I have to say it's quite amazing. How you've managed to cover such a wide breadth of regions and topics at such detail, all the while keeping a relatively fast pace and the story moving, is truly astounding.
On this last update, as well as topics yet uncovered, I'd like to share some thoughts and questions.
First regarding the expansion of the Zollverein I'd expect some resistance from the SPD fearing the danger of loan dumping due to unskilled immigration from the east (might be explained by immigration restrictions) and the flooding of German markets by cheap agricultural products harming a voter base they're just trying to capture (as mentioned in the update regarding the Prussian juncker estates).
On the issue of 'Kingdom' or 'Archduchy' (or whatever) I'd be rather skeptical of the Austrians/Habsburgs accepting a 'King' as there's really no historical precedent for it. This issue has been discussed a few times on the board but there doesn't seem to be a consensus. Considering that 'Cisleithania' was an informal name for the official 'The Kingdoms and Lands represented in the Imperial Diet' it would probably be something ham-fisted like that while colloquially 'Archduchy of Austria' would be used.
Finally, I'm curious how female suffrage is progressing as we're getting deeper into the 20s and I'm looking forward to the update on developments in science and technology (e.g. what's Fritz Haber up to now that he isn't trying to create gold from water to repay Germany's war reparations?).
That is absolutely fantastic to hear, I do put a good deal of time into preparing it so seeing it appreciated is always great.
While the SPD is trying to break into the rural voting base, for the time being it is more of an issue on the right, particularly with the DKP and DNVP who have significant junker backing. Furthermore, the harm done to the rural voter base by cheap agricultural produce is more than made up for by the positive reactions on the part of urban populace who are able to enjoy cheap food. The flood of cheap food is part of the general euphoria of the 1920s, with many enjoying their freedom to enjoy food given the near-starvation faced by many during the Great War. Additionally, the Zollverein doesn't include migration provisions - it is a trade, customs and tariff union. Not quite the EU Four Freedoms. That said, there is a good deal of unskilled migrant labor from the east, but not as many as you might expect given the German exploitation of natural resources in Eastern Europe requiring a great deal of local labour force.
On the issue of Kingdom v. Archduchy, the issue with that title has more to do with historical accident than an unwillingness of the Habsburgs to make Austria a kingdom. When they only held Austria, there were several attempts to have the Archduchy elevated, but this was met with considerable resistance on the part of other powers with an interest in holding back the Habsburgs. By the time the Habsburgs had the power to elevate the Archduchy, they were already kings several times over and as such saw little need to elevate the title. As for there being no historical precedent, I could say the same for Bavaria, Saxony or Württemberg when they were elevated.
You are correct on the usage of Cisleithania being a bureaucratic term not used outside of a very limited circle of people, although they also wouldn't have used Archduchy of Austria - they would have used "Austrian Lands" instead, which excluded the Bohemian Crown Lands, Dalmatia and Galicia. The Austrian Lands are the lands absorbed by Germany ITTL. Those lands were not referred to as being a single Archduchy - hell, there are two Archduchies within the Austrian Lands, Upper and Lower Austria.
I have a book called The German Genius by Peter Watson which deals with the development of German intellectual and scientific thought from Friedrich the Great and until the end of WW2 (might go further than that, but I haven't gotten into it in any great detail quite yet) which I hope to draw on inspiration for. I am not sure what Haber will be doing tbh. As for female suffrage, thanks for reminding me, I will have to include a section on it.
While there are several maps, they are only regional, and spread across different updates, so a proper world map would be nice. There is no map for the Middle East, for example, other than the one showing the Persian partition (unless i have overlooked it?). I would volunteer to make a map, but i use an iPad, and have unfortunately no idea what program to use, lol.
I don't trust myself to make a full map tbh, which is why I have been limiting the focus to regional maps as much as possible. That said, if anyone wants to take the initiative, I am happy to help in any way possible. I would love a world map but I just don't have the knowledge, time or talent for it.
