9.2 Rapid Increase in Global Population

Population Boom After 1900

The global population grew explosively in the twentieth century, especially after 1945, rising from about 1.6 billion in 1900 to over 6 billion by 2000. This surge resulted from declining death rates while birth rates remained relatively high, especially in developing regions.

Causes: Medicine, Food, and Sanitation

Advances in medicine and vaccination reduced deaths from disease, while the Green Revolution boosted food production through new seeds, fertilizers, and irrigation. Improved sanitation, clean water, and public health infrastructure lowered infant mortality and extended life expectancy worldwide, fueling rapid population growth.

Uneven Growth and Responses

Population growth was uneven — faster in Africa, Asia, and Latin America than in industrialized nations, some of which saw declining birth rates. Rapid growth strained resources, housing, and jobs, prompting some governments (like China's one-child policy) to implement population control measures, while others encouraged growth.

Key terms

Green Revolution

A mid-1900s agricultural movement using new seeds, fertilizers, and irrigation to dramatically increase food production.

Reasons for population growth

Declining death rates due to medical, sanitation, and food advances, while birth rates remained relatively high.

China's one-child policy

A government program limiting most families to one child to slow rapid population growth.

Uneven population growth

Africa, Asia, and Latin America saw faster growth than industrialized nations in the twentieth century.

Effects of improved sanitation/medicine

Lowered infant mortality and increased life expectancy, accelerating population growth worldwide.

Try an AP-style question

Global population grew rapidly in the 20th century mainly because of…

1. rising death rates
2. fewer medical advances
3. declining birth rates everywhere
4. falling death rates