Natural increase is the difference between the number of live births and deaths in a population over a given period, leaving migration out entirely. On the AP exam it usually appears as the rate of natural increase (RNI), calculated as crude birth rate minus crude death rate, expressed as a percentage.
Natural increase measures whether a population is growing or shrinking on its own, based only on births and deaths. Migration doesn't count. If more babies are born than people die, natural increase is positive. If deaths outnumber births (like in Japan or much of Eastern Europe), it's negative, which geographers call natural decrease.
On the exam you'll almost always see it as the rate of natural increase (RNI). The math is simple. Take the crude birth rate (births per 1,000 people), subtract the crude death rate (deaths per 1,000 people), and convert to a percentage by dividing by 10. So a country with a CBR of 35 and a CDR of 10 has an RNI of 2.5%. That sounds small, but a 2.5% RNI doubles a population in roughly 28 years. RNI is basically a country's demographic speedometer, and where a country sits on the Demographic Transition Model predicts the reading.
Natural increase lives in Unit 2 (Population and Migration Patterns and Processes), where you analyze population growth and decline using measures like CBR, CDR, and RNI. It's the bridge concept that makes the Demographic Transition Model work. Stage 2 countries have high RNI because death rates crash while birth rates stay high; Stage 4 and 5 countries hover near zero or go negative. The College Board has tested it directly. The 2017 FRQ used a world map of natural increase rates as its stimulus, and the 2023 SAQ opened by defining RNI as the tool geographers use to assess annual population growth or decline. If you can't read an RNI map and connect it to development levels, you're leaving Unit 2 points on the table.
Birth Rate and Death Rate (Unit 2)
These are the two ingredients of natural increase. RNI is literally CBR minus CDR, so any factor that moves either one (women's education, healthcare access, pro-natalist policy) moves natural increase too.
Population Growth Rate (Unit 2)
Total population growth is natural increase plus net migration. A country like Germany can have negative natural increase but still grow because immigration fills the gap. The exam loves this distinction.
Developing Countries and Economic Development (Units 2 & 7)
High RNI clusters in less developed countries, especially Sub-Saharan Africa, because they sit in Stage 2 of the DTM. As economies develop and women gain education and workforce access, fertility falls and RNI shrinks. This is the demographic side of the development story you'll see again in Unit 7.
Brain Drain (Unit 2)
Natural increase ignores migration, but real population change doesn't. A high-RNI country losing skilled workers to emigration may grow naturally while still hollowing out its labor force. Pairing the two concepts makes for stronger FRQ analysis.
Natural increase shows up in both multiple choice and free response. MCQs typically give you CBR and CDR numbers and ask you to calculate or compare RNI, or show a choropleth map and ask which region has the highest natural increase (expect Sub-Saharan Africa as the answer). On FRQs, it's a stimulus workhorse. The 2017 FRQ built an entire question around a world map of natural increase rates, and the 2023 SAQ asked directly about RNI as a measure of annual population growth or decline. To earn points, you need to do three things. Define or calculate RNI correctly. Explain why a region's RNI is high or low using DTM stages or development factors. And remember the trap that RNI excludes migration, so it isn't the same as total population growth.
Natural increase counts only births minus deaths. Population growth rate adds net migration on top. A country can have negative natural increase and still grow (Germany, with heavy immigration), or positive natural increase and shrink (a high-emigration country). If an exam question mentions migration, RNI alone won't answer it.
Natural increase equals births minus deaths in a population, and it completely excludes migration.
The rate of natural increase (RNI) is calculated as crude birth rate minus crude death rate, divided by 10 to express it as a percentage.
A negative RNI means natural decrease, where deaths outnumber births, which is common in Stage 4 and 5 countries like Japan.
High RNI is concentrated in Stage 2 developing countries because death rates fall fast while birth rates stay high.
Total population growth equals natural increase plus net migration, so a country with negative RNI can still grow through immigration.
The College Board has used natural increase as FRQ stimulus material, including a world RNI map in 2017 and a direct RNI question on the 2023 SAQ.
Natural increase is the difference between live births and deaths in a population over a period of time, with migration excluded. As a rate (RNI), it's crude birth rate minus crude death rate, expressed as a percentage.
Subtract the crude death rate from the crude birth rate, then divide by 10 to convert from per-1,000 to a percentage. Example: CBR of 35 minus CDR of 10 gives 25 per 1,000, or an RNI of 2.5%.
No. Natural increase only counts births and deaths, while total population growth also includes net migration. Germany has negative natural increase but its population has grown in some years because of immigration.
Yes. When deaths outnumber births, a country experiences natural decrease, which shows up as a negative RNI. This happens in Stage 4 and 5 countries like Japan and much of Eastern Europe with aging populations and low fertility.
Yes. The 2017 FRQ used a world map of natural increase rates as its stimulus, and the 2023 SAQ asked about RNI as a measure of annual population growth or decline. MCQs often ask you to calculate RNI or read it off a map.