How many people worked in the secondary sectors over 100 years ago?

Over 100 years ago, specifically around the early 20th century, a significant portion of the workforce was employed in secondary sectors, including manufacturing, construction, and mining. In the United States, for instance, about 30% of the labor force worked in these sectors during this period. This was a time of industrialization, where many people transitioned from agriculture to factory jobs as economies shifted towards industrial production. The exact number varied by region and country, influenced by local resources and economic development.