Midlatitudes: the regions between 30° N and 60° N, and between 30° S and 60° S.

Low Lying Areas: place at or near sea level

Fresh Water: People need fresh water to drink, irrigation, transport, and provide food.

Arithmetic population density: dividing a region’s population by its total area.

Physiological population density: dividing population by the amount of arable land, or land suitable for growing crops.

Carrying capacity: the population it can support without significant environmental deterioration.

Overpopulation: having more people than it can support

Agricultural population density: the number of farmers in the area of arable land.

Birth deficit: The slowdown of births (during the war)

Baby boom: the birth rate spikes (once the war is done)

Baby bust/Echo: Once the boom ends, births are lower for a number of years/ With a high number of boomers in the population having children, there can be a significant increase in births.

Dependency ratio (DR): comparing the working to the nonworking parts of a population.