What primarily led to the decline of the U.S. whaling industry after the Civil War?

The decline of the U.S. whaling industry after the Civil War can largely be attributed to the discovery of oil and natural gas in Pennsylvania. This discovery, which took place in the mid-19th century, marked the beginning of the petroleum industry. As oil became commercially viable, it emerged as a major substitute for whale oil, which had been used for lighting lamps and as a lubricant. The availability of these new energy sources meant that the demand for whale oil significantly decreased. Furthermore, the rise of kerosene as a popular household lighting source diminished the economic viability of whaling, which had previously been an important industry.

While changing fashion trends and substitutes also played a role in the decline, the introduction of affordable and widely available oil products had a more profound impact. Rapid reductions in whale populations due to better technology for hunting did contribute to a decline, but the primary factor remains the shift in energy sources following the discovery of oil. Loss of ships to Confederate raiders affected the fleet available for whaling temporarily but was not a long-term cause of industry decline like the rise of the petroleum industry.