The 2010 census data are resulting in a plethora of local news articles about population growth and decline. Many community leaders are cheering because their communities had a population increase. As sports commentator Lee Corso would say, “Not so fast my friend.” Population increase alone is misleading if migration is not also considered. So what is “migration?”
Migration refers to the movement of people from one area to another. To calculate the migration for a community take the current population, subtract the previous population, add the number of births during the period, and then subtract the deaths during the period. Consider this example of a fictional community I’ll call Center City:
52,000 2010 Population
50,000 2000 Population
2,000 Population increase
Most people would say that a population increase is a good thing for a community. In general, that would be true. But what if Center City had 3,000 births during the 10-year period and 900 deaths? The difference in those two numbers is 2,100, which is how many new residents there would be if somehow a wall had been around the city. In other words, Center City would have a natural population increase of 2,100. But it only grew by 2,000. What happened to those 100 people? The answer is that they moved away, which is another way of saying that there was out-migration. Conversely, if the population increase is greater than the difference in the number of births and deaths there is in-migration.
In summary, failing to consider migration could lead to a misinterpretation of a community’s true growth trend.