In this lesson, you will discover how to see the future through population statistics. Explore population projections, and test your understanding with a brief quiz.

## Projected Population

Ever wonder what the future will look like? Flying cars, robots, colonies on Mars.

I’m really hoping for all three. But what about future populations? What will they look like? Will the cities be even more crowded than they are now? Will there be equal numbers of men and women? How long will these people live?Well, guess what? We don’t just have to wonder. Amongst the statistics published by many censuses around the world, including our own, is a **population projection**, a prediction of future population trends based on current data.

Basically, we take current **demographics**, statistics on a population, and use them to predict future trends.Now, really quick, it’s important to make a distinction between projections and **population estimates**. A projection is a future prediction; an estimate is an approximate current population. It’s important not to get these mixed up, since estimates are often used to create projections. Got it? Okay, let’s go see the future!

## U.S.

Projections

Want to know what the future may just look like for us here in the good ol’ US of A? The U.S. Census Bureau, the department in charge of population statistics, puts out a report every year. You can find all of this on their website, if you’re ever interested.So, what’s the future look like? According to the population projections that were released in July 2015, our current population of roughly 319 million is expected to hit 400 million by 2051.

While that may seem like a lot, it’s actually a lot slower rate of growth than we’ve had over the last several decades, at an average of only 0.4% per year.What else? Well, by the year 2020, less than half of American children are expected to identify as non-Hispanic white, meaning that Anglo Americans are projected to become an ethnic minority by the year 2060. It looks like another major milestone will come in the year 2029, when the baby boomer generation will officially all be 65 or older. This is a large part of our population, so that means that by 2030, one in five Americans will be a senior citizen. Right now, only one in seven Americans are over the age of 64.

## Calculating Population Projections

So, that’s our future! At least, that’s what we project it to be. But how on Earth do we predict those sorts of things? It’s not like the Census Bureau has a crystal ball in the basement that shows future demographic reports.Or do they? No – the preferred method for creating a population projection is the **cohort-component method**, a formula that uses current population estimates to project future populations. The basic idea is that each **component of population change**, like birth, death, and migration, is calculated individually for every **cohort**, or people born within a certain date range. The U.

S. Census Bureau uses a cohort of one year, say everyone born in 2015, but other projections may use ranges of five or ten years.So, every year you take the actual population and predict the rates of birth, death, and net migration for each future cohort. But what do each of these mean? Okay, first is the actual, or **survived population**, the number of people expected to be alive. So, right now, we’d say there is a survived population of 319 million people.

But, assume that about 2 million people die every year, that takes us down to a survived population of about 317 in 2016. However, now we add new births, which is predicted at roughly 4 million, so the projected population for 2016 is roughly 321 million.See how this works? Now, there’s one last step, and that’s **net migrations**, or the increase or decrease in population from immigration and emigration. The U.S. Census Bureau has the net migration right now at just over a million, so now our projected population is around 322 million people in 2016.

We do this for every year into the future and build up a long-term projection.That’s the basic idea behind the cohort-component method, although obviously we’re far from done. For example, how exactly do you figure out the predicted number of births for a year? This is more complicated and involves multiplying fertility rates by the female population within a certain age range.

The number is then entered into another formula to predict sex ratios, or the number of expected males and females born in that year, which helps determine future fertility rates, and it goes on and on.There are quite a few different calculations that go into the final projection, but really the only one you need to remember is the basic cohort-component equation for a given year, which looks like this: total population = surviving population + births + net migrations. And with that, you, my friend, have got a glimpse of the future.

## Lesson Summary

A **population projection** is a prediction of future population trends based on current data. The U.

S. Census Bureau publishes one of these every year, usually in July. Most population projections use the **cohort-component method**, a formula to predict future populations. This method creates projections for each **cohort**, or range of years by individually calculating each **component of population change**, birth, death, and net migration. So, the formula for each cohort looks like this: total population = surviving population + births + net migrations. By using this formula, statisticians can build a projection one year at a time. And with that, we can see the future.

Who needs a crystal ball?