You also conquered a bunch of people. Added their lands and peoples to yours.So looking at the numbers, our amount of citizens has increased by 20% in 15-20 years since we started all those subsidized farms and ranches. More plentiful food makes people want to have more kids. Who knew?
By next census we should have passed the 2 million mark for total population.
With more people come more military forces and more taxes.
Can't really say where the population increase is coming from.
For reference, at a growth rate of 2.5%, you'd double your population in about 25-28 years.
So your population growth isn't really that fast atm.
Better hope a disease event doesn't trigger.
Like plague. Or influenza. Or cholera. Or salmonella.