Each city has a population , encoded as a small positive integer. Population is quantified in population points of 1 population each. Players often refer to population as just pop.
Population growth is computed in the game via an intermediate mechanism called the food bar. The food bar represents a stockpile of food in that city. When a city produces more food than its population eats, it has a food surplus; this extra food is added to the food bar each turn. When the food bar is filled, the city will normally grow (gaining 1 population). This will not happen, however, if the "don't grow" option on the city has been selected. When a city grows and it does not have a Granary, the food bar will be reset to zero, plus any overflow. If the city has a Granary, the food bar is reset to whatever amount is in the granary (usually, to half-full), plus overflow.
In addition to the normal mechanism of pop growth as above, there is one other way that pop increases in the game: when the Hanging Gardens is completed, every city in its civilization gains 1 point of population.
There are several ways in which a city can lose population:
Starvation is mediated by the food bar. The food bar cannot go negative. If the city has a food deficit , and the deficit would be enough to cause the food bar to go negative, instead it is set to zero and one point of population is lost. Note that the same effect happens no matter how large the food deficit is: a city can never lose more than a point of population per turn, no matter how bad its food deficit is.
Effects of Population
There are many effects of a city's population. These are summarized here:
- each point of pop eats 2 food per turn, or 3 food each for unhealthy pop
- each point of pop adds to a city's unhealthiness
- happy population can produce via working tiles or being specialists
- the values of a city's trade routes increase when its pop goes above 10
- a city cannot draft if below 6-8 population
- a city cannot whip if the whip would kill more than half its population
- more populous cities are favored by the algorithm which selects the holy city when a new religion is founded