There have been numerous media reports about the recent estimate from the U.S. Census, which shows that Harris County was the fastest-growing county in the country last year. While some of the stories mention the importance of international immigration in passing, I did not find any that reported that essentially all of the growth was due to people moving to the County from other countries.
In its estimates, the Census Bureau breaks down the components that make up the changes in population. These are natural growth (births minus deaths), domestic immigration, and international immigration. Domestic immigration refers to people moving between locations within the United States. International immigration involves a person moving into a jurisdiction from another country. The Census Bureau does not distinguish between legal and illegal immigration. Here is what the Census Bureau’s estimate showed for Harris County.
This actually understates the impact of international immigration on the County’s growth because immigrants prop up the natural growth. Immigrant mothers tend to have larger families than mothers born in the U.S. This Pew study found that essentially all of the increases in births in the U.S. since 1970 are attributable to immigrant mothers. Without international immigration, Harris County would likely have lost population last year.
The Census Bureau estimated that international immigration increased Texas’ population by nearly 320,000 last year. This implies that about one-third of all international immigrants who arrived in Texas settled in Harris County.
It is noteworthy that Harris County had a net domestic out-migration. This represents the difference between people moving into Harris County from somewhere else in the U.S. and those moving out of Harris County to somewhere else in the U.S. This is the eighth consecutive year that the Census Bureau has reported a net domestic out-migration for Harris County. Over that time, the County has lost about 200,000 residents to domestic out-migration.
However, the estimates for the counties surrounding Harris County show a very different pattern. The population of the seven other counties in the Houston MSA grew by 90,000 last year, but international immigration accounted for only 29% of that growth. All of these counties experienced positive domestic migration, which accounted for 57% of their population growth.
The importance of immigration patterns on our region’s population growth cannot be overstated. Last year, natural growth was only 48,000, representing a growth rate of 0.6%. If current trends persist, natural change will continue to decline; therefore, immigration — whether domestic or international — will have an even greater impact on population growth or, perhaps, decline.
When I speak with my fellow Houstonians, I find that there is a nearly pervasive belief that Houston will continue to grow indefinitely, with few aware of the outsized role international immigration has played in recent years. However, this data suggests that if there is a dramatic change in immigration policy, as the Trump administration has promised, that belief is highly questionable.
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Research Note: The Census Bureau estimates are grouped by state. This is a link that will open a spreadsheet for Texas. This is a link to a spreadsheet that I have prepared, which pulls out just the counties in the Houston MSA and those included in the Houston-Galveston Council of Governments (HGAC).
