(April 2000) The role of immigration as a source of U.S. economic strength is projected to increase dramatically following the next couple of decades as the youngest baby boomers move into retirement.

As longevity improves and the last of those born in the post-World War II fertility boom become pensioners, declines in the availability of workers will force a response in U.S. policy, U.S. Census Bureau projections indicate.

As this large population of former workers cash in on social security, a substantial increase in the number of immigrants will be necessary after 2020 to make up for the sharp reduction in economically productive people, the Bureau projects.

“Our projections anticipate an increase in the influx of migrants to the United States as a response to this dramatic downward shift in the availability of potential workers relative to people outside the normal working ages,” according to the Bureau’s report, Methodology and Assumptions for the Population Projections of the United States: 1999 to 2100.

If people continue to retire in their mid-sixties, the youngest of those born in the highly fertile period of 1946 to 1964 will have recently begun to receive pensions in the 2020s. The oldest among them will be approaching their mid-70s by 2020 and their mid-80s by 2030. And since people are increasingly healthy and living longer (life expectancy is projected to be around 80 years old in 2020), a large percentage of these boomers may still be drawing down state-sponsored benefits.

With birth rates expected to remain close to the current rate of 2.0 children per woman, the projections do not anticipate a significant rise in the labor force once this pool of workers make their exit. At the peak of the baby boom era in 1957, women were having an average of 3.8 children. The rate is projected to be 2.2 children by 2025, according to the Census Bureau’s mid-level assumptions.

The Bureau projects that the most pressing need to fill the gaps left by the aging boomers will occur between 2020 and 2030. Mid-level estimates for net international migration show a decline, from roughly 1 million people in 1999 to three-quarters of a million by 2020. The Census Bureau projects a dramatic shift, however, between 2020 and 2030. Those 10 years could see a 41 percent increase, with net migration jumping back to roughly 1 million.

The Bureau uses different scenarios to make its predictions, including one that assumes a balancing out of migration into and out of the United States. Under this scenario, the ratio of persons in their economically dependent years increases roughly 16 percentage points between 2015 and 2030 or an average of over 1 percentage point each year. The dependents-people less than 15 years old and more than 64 years old-require schools, pensions, and other social programs. This sector of the population increases from 53.0 percent in 2015 to 69.4 percent by 2030.

When the Bureau uses mid-level immigration numbers, the ratio of persons in their economically dependent years increases more slowly, rising 13 percentage points instead of 16 between 2015 and 2030.

The Bureau says it is the increase in economically dependent people relative to those in their working years that will drive an increase in migration to the United States. While the 41 percent projected rise in international migration between 2015 and 2030 is large in percentage terms, however, the increase is modest from a historical perspective.

“The migration response to the economic boom of the 1920s in the United States, and the labor migration from southeastern to northern Europe in the period following World War II are examples of migratory shifts far more dramatic than the one projected here,” says the Census Bureau.

Yvette Collymore is a senior editor at the Population Reference Bureau.