“The history of all hitherto existing society is the history of class struggles.”
What is a POP anyway? POPs are the basic population units in Victoria. They are in every country and every populated province. They are the basis for your entire economy. In fact, they are your economy. POPs come in various sizes, from 1 to 100,000.
POPs come in ten flavors: Officers, Aristocrats, Capitalists, Clergymen, Clerks, Craftsmen, Farmers, Laborers, Soldiers, and Slaves. Each contributes in different ways to your economy. Most POPs are convertible by you, the player, assuming they are at the right level already and you have the resources to promote them to the next.
What do the different POPs do?
Note that most POPs that give certain bonuses (i.e. Clerks granting research points) must be of one your National Cultures for you to receive that bonus.
Aristocrats and Capitalists are considered “Rich”; Officers, Clergymen, and Clerks are considered “Middle Class”; and Craftsmen, Farmers, Laborers, and Soldiers are considered “Poor”. This is important to keep in mind when deciding how much to tax each class of your citizenry. Slaves, as mentioned earlier, are not taxable.
POP merging is one of the more controversial concepts of the POP system. Merging takes place between POPs which are less than 10,000 in size and essentially prevents a situation that there are dozens of small, hundred or thousand person POPs, in a province. An under-10,000 POP can merge with a larger POP as long as the resulting POP is not larger than 100,000. When any two compatible POPs (that share the same culture, religion, and type - i.e. Clerk, Craftsman, Farmer) are located in one province, they may merge and form a single, larger POP, as long as at least one of them is less than 10,000 in size. In other words, if both POPs are bigger than 10,000 they will never merge (although one of them can merge with another, small one). Merging will lower POPs combined production output so it's best to avoid it if you can.
The direct effect of POP merging is that industrialization is easier in multi-ethnic empires, as the small POPs of different cultural groups will not merge, thus creating more available POPs to place in factories. Since a 500 person POP is just as efficient in the factory as a 19,999 person POP, this kind of multi-ethnic industrialization can make a big difference in production.
POPs not only merge but split as well. When a POP grows to be 100,000 in size, it will split into one 25,000 person POP and one 75,000 person POP, each of which will continue to grow as separate entities, eventually splitting themselves once they reach 100,000 again. This is how the game simulates population growth.
POPs can also degrade (devolve). If a specific POP is taxed too high (above 55% of its income) AND some other conditions are met (notably satisfying POP's needs) it will devolve into a "lesser" POP. In other words when you tax POPs below 55% they will never devolve, no matter what. When you observe middle and/or rich strata POPs decrease in size by a small amount every few days while your poor strata POP in the same province increases in size by the same amout you may be sure it's devolvement. Thus it is wise to never overtax your upper and especially your middle class unless you know what you are doing.
How do POPs produce? POPs add to your production output by working directly in either factories or in RGOs. Neither will produce goods without POPs to work them. When choosing which POPs to assign to a particular factory, you must keep in mind the POP’s size. Different sizes of POPs produce more than others (see section “Industrialization”). Every factory or RGO can accommodate only five POPs per level, regardless of their size.
Another factor to keep in mind is that you are limited in the number of clerk POPs compared to the number of craftsmen POPs in a factory. Clerks are more beneficial to you, so if possible you should always try to aim for the maximum allowed number of clerks (both in number of POPs and POP size).
POPs will not remain forever in one province. If they are unemployed, they will eventually seek work elsewhere. All POPs migrating are programmed to seek jobs within your country first, then in your country’s colonies, and lastly in other countries (this is called emigration). This way, if you have open factory slots in one state and unemployed Clerks and Craftsmen in another, they may migrate to the open jobs. Keep in mind that this process, as in real life, is not perfect and many POPs will not always go where you want them to. When you see an unemployed POP that decreases in size every month and some other compatible POP (the same culture, religion and type) in a different province increases in size by the same amount you are observing an (internal) migration. When such POP disappears from one of your provinces and doesn't show up in any of your provinces you are probably observing emigration, your people found a better place to live in another country. Ledger, page 17, contains migration overview in the last 30 days.
POP migration is also affected by the life ratings of your provinces (the little thermometers), which show how good they are for human habitation. The better the life rating of the province, the more people will want to move there.
POPs' concerns and needs
All individual POPs come with individual thoughts and issues. Each POP will tell you what their specific issues of concern are, what chance they have to revolt, and how politically conscious they are of themselves. Each POP type also comes with its own demands for specific goods. These are in three groups: life needs, everyday needs, and luxuries. The more of each they get, the less likely they are to revolt and the more you tax them, the less they can buy. The specific goods that fall into each class can vary by POP type. For example, Farmers, unlike all other POP types, have fertilizer set as a luxury good.