Ask about “the population problem” to people of a certain age, and the first and perhaps only thing that comes to mind is the “population bomb” or “population explosion.” And they would be right - for their time. In the second half of the 20th century, rapid population growth - especially but not exclusively in the developing countries - created unprecedented increases in the number of people on the earth. And this growth was accompanied by crowding, malnutrition, disease, and poverty. Indeed, ...

Ask about “the population problem” to people of a certain age, and the first and perhaps only thing that comes to mind is the “population bomb” or “population explosion.” And they would be right - for their time. In the second half of the 20th century, rapid population growth - especially but not exclusively in the developing countries - created unprecedented increases in the number of people on the earth. And this growth was accompanied by crowding, malnutrition, disease, and poverty. Indeed, for many Americans, the coming “population explosion” was, along with the Cold War, the most unsettling fact about our world.

But “population problems” have been part of American discourse for over 100 years. In the 1930s and 1940s, for instance, many observers feared that depopulation due to plummeting birth rates would cause chronic economic depression as the numbers of U.S. consumers and workers declined. In the 1920s, the U.S. “population problem” was rapid urbanization, reflected in a 1920 census count showing that for the first time more than one-half the population lived in urban areas. Rural incumbents in the House of Representatives, fearing they would be voted out of office by their new urban constituents, succeeded in blocking reapportionment of the House’s seats on the basis of the census counts as mandated by the U.S. Constitution.

The century’s first “population problem” was mass xenophobia about immigration. Beginning in 1880, wave after wave of European immigrants was creating congestion and social change at an unprecedented rate. In response to widespread anxiety and anger, Congress in 1924 passed the country’s most restrictive immigration legislation ever. Each problem was based in hard numbers. Each generated private emotions and public fears. Each suffered exaggeration and manipulation. And each commanded the attention of opinion leaders and elected officials.

(Source: https://www.prb.org/)

Which best serves as the title for the passage?