The market of Mechanical calculators
(overview countries, regions, time windows and manufacturers)

Germany before and after first world war (WW1)
Before WW1 there already were some German companies producing office machines (e.g. S&N, Wanderer).
After WW1 most German weapon factories were demilitarized, as part of the Versaille treaty. Those manufacturers had production skills and capabilities to design and build precisian mechanics, some of them (e.g. Rheinmetall Sömmerda, Preussische Gewehrfabrik Erfurt) decided to produce office machines.

Europe before the second world war (WW2)
The fine-metal processing industry and particularly the production of office machines, such as typewriters and calculators, as well as the production of cameras and clocks, was in Europe, before the second World War (1938), 75% owned by companies of the former German Democratic Republic (GDR). Companies who build mechanical calculators, were already active in the car and bicycle manufacturing and sometimes in arms industry. Names of important companies are: Astra, Brunsviga, Wanderer / Continental, Olympia, Thales, Triumphator, Rheinmetall, Walther and Mauser. The last three were at that time, into arms manufacturing as well.
Although in the US Frank Baldwin is getting the credits for the Pin Wheel development, in Europe the design is given to the Swede W.T. Odhner. Odhner worked at Nobel and had patented the Pin Wheel or Sprossenrad in German, and asked his boss Alfred Nobel (Yes indeed, the one of the famous achievement award), if he may have production capacity for his design. He got those in St. Petersburg, were the first machines were built for the Russian and European market.
After the Russian Revolution several of those licenses in Russia became worthless and the Russians continued production under the brand name Felix. Odhner moved his production to Sweden (Gothenburg).
In Germany license rights sold to Frans Trinks (from Braunschweig), which produced since then very successful the Brunsviga for the whole European market. In 1938 Sweden, Switzerland, France and Italy (Olivetti) were more or less responsible for the relative rest (15%) of the European market. A selection of the companies who were on the marked are listed on this site.

Due to the enormous weight, 20 kilograms and more, and a not yet flourishing trade with the US and Japan, the USA owned companies had a share of less than 10% in those years in Europe. Big names in the US were Burroughs, Dalton, Sundstrand and Victor. These companies hold many patents and produced until the fifties mainly for their American home market .
In the US, St Louis Missouri was the area of fine metal industry and therefore important in mechanical calculating history. Baldwin, Monroe, Burroughs, Standard, Dalton, Moon Hopkins, Pike and Remington Rand had their production plants here.
(has to be completed with info about manufacturers like Friden and Marchant)
Under the post-war European reconstruction plan (the Marshall Plan) Monroe and Burroughs established new factories in Europe: Holland, UK, France and Italy.

During and after de second world war, in the former GDR
During the Second World War, most German companies stopped their office machine production (e.g. Astra, Wanderer, Rheinmetall).. They were forced to switch production and take part in arms production for Nazi Germany. They severed hard times due to the allied bombing of factories and homes. That's why there are nearly no new German office machine models between 1938 and 1945.

After WW2, and this is not commonly known in the west, dismantling of the factories and infrastructure by the Russians toke place. Drawings, machinery, supplies, materials and sometimes even the management had to go to Russia. Railway's where partly dismantled etc. When a company was able to produce, they were forced to deliver these to Russia.
A lot off Eastern Germany management refuge to Western Germany. Many of them started and won juristic processes about the trade marks against their former companies. That's why most companies at East-German territory had to change their trade marks in the 1950s (Rheinmetall -> Supermetall / Soemtron, Mercedes -> Cellatron, Astra / Wanderer -> Ascota).
But the GDR companies were able to withstand these severe conditions, which was a remarkable achievement and not well realized in the western countries.
An other issue, they had to cope with, was the restructuring of these private owned companies, to state own companies, the so called VEB's (Volks Eigener Betrieb). These where continuously merged for optimization of resources and production to combinations of VEB's. The ministries became responsible for the policies and made these companies less accurate responding to the markets and technical developments in the west. Even electronic companies where attached to the mechanical oriented manufacturers. All this lead to a massive industry which was controlled by the government. The switch to those micro electronics technologies, was made at a to late stage. Their electronic products were not bad at all, but came to late to be competitive on the market to compete with the US and Japanese ones.

The glory and the downfall
The fifties, sixties and early seventies are the glory years of the mechanical calculator industry. Booming conjunctures results in big growing markets. These contributes to successful years for the industry. Optimization in terms of production, machine reliability, -weight and calculator speed, lead to smaller and cheaper calculators. Prices became acceptable for massive use in the every type of companies to even small private owned businesses.
The emerging office and hand held calculators from America (e.g. Texas Instrument and HP) and Japan, took much market share in the early seventies. *)1
The GDR, as earlier mentioned, companies mergers. These combination of companies, had put massive efforts in mechanical calculator design. After changing country leadership (Ulbricht - Honecker) budget shortcuts were fact. Just on the time heavy technology research in the electronics was needed. Due to the technologies boundaries with the western developments, not even the transistor was locally available, mechanical calculators designs get more advanced functionality in the GDR. *)2
Examples of this are:

After the introduction of the micro electronics, the end of the 70’s, the production of mechanical calculators were stopped in the GDR as well. A lot of companies shut down or gone in other industries. For example: Wanderer to Auto Union the later Audi. A small part in the Nixdorf computer company, the later Siemens Nixdorf. In Italy Olivetti have moved to the desk-top computer market. And the American companies, for instance Burroughs, merged with a number of companies under the name Sperry, later Unisys, to the US mainframe computer manufacturer.

Manufacturing is often production skills driven. Research in alternative technologies is often a small side activity, with a blinkered view to fundamental other possibilities. Transitions to modern technologies are often made in a to late state. There are several industrial revolution examples: cotton textile to synthetic textile; steam to electric trains; iron to alloy;  mechanical to electronic; bank to tele bank; travel shop to web-shop; post to e-mail,  etc, etc.
The reason behind this is the often seen natural attitude of management stayed to long in office. They :

All traditional clincher! They / people / we, tend to fall repetitive in the same pitfalls!
The transition from mechanical to electronic calculators was no exception. And earlier the transition from full keyboard to ten key ones, was for instance not realistic and not ruggedized enough, according the management of Wanderer-Continental of those days. The beginning of their end in the business.

A few western companies like Olivetti, Olympia, Precisa and Walther as well continuing their development in Rocking segment technology machines, during the early electronic ages, with a automatic multiplication and division functionality. But although these machines are sophisticated, they considered not as advanced as the programmable bookkeeping ones.