The Industrial Revolution did more than just invent new materials or machines. It invented a new process for manufacturing: the modern factory. Prior to around 1850, most piano shops used an apprentice system in which a master builder taught younger workers the skills of the trade, usually over the course of many years. The larger piano shops did have specialists ─ for example, one person who specialized in soundboards, another who made hammers, and so on. But even the largest piano makers of that time produced no more than 5-10 pianos per year per worker, as pianos were still made essentially one at a time. The development of a true piano factory occurred first in the United States, led by Jonas Chickering in Boston and later the Steinway family in New York City. These factories led to improvements in both efficiency and quality. For example, one of the factories of the time had its own iron casting facility where it made its metal plates, which were thought to be the best available.