Why did the discovery of the Witwatersrand Main Reef lead to Johannesburg’s rapid growth?

The discovery of the Witwatersrand Main Reef in 1886 transformed the region into the 19th century’s last great boomtown, Johannesburg, primarily due to the massive scale and economic potential of the gold deposits.1

Following the initial discovery by George Harrison, an influx of fortune seekers, skilled miners, and laborers descended upon the area, rapidly expanding the population to 100,000 by 1896. Unlike other gold rushes that relied on individual prospectors, the geology of the Witwatersrand required significant capital, technical expertise, and heavy machinery to extract and process the low-grade ore.123

This necessity led to the consolidation of small mining operations into powerful corporations controlled by "Randlords," who established a stable, large-scale industrial mining economy. Because these operations were not short-lived like those in North America or Australia, the industry provided a sustained economic foundation that allowed Johannesburg to grow from a makeshift mining camp into a permanent, major city.231