Glass mirrors have been used since the 17th century. The era when glass mirrors became widely used in the United States can be traced back to the late 18th and early 19th centuries. This period, often referred to as the Federal period (1789-1829), saw a significant increase in the production and consumption of glass mirrors. The introduction of the crown glass process in the late 18th century revolutionized the glass-making industry, making it possible to produce large, flat, and high-quality glass mirrors.

The Federal period was marked by a surge in domestic manufacturing and a growing middle class. As people's incomes rose, they began to purchase more consumer goods, including glass mirrors. According to the U.S. Census Bureau, the number of manufacturing establishments in the United States increased from 1,435 in 1790 to 8,631 in 1820. This growth was accompanied by an increase in the production of glass, which was used in various applications, including mirrors.

The use of glass mirrors in the United States during the Federal period was also influenced by architectural trends. The Federal style, which was popular during this time, emphasized symmetry and geometric patterns. Glass mirrors were often used to enhance the symmetry of rooms and to reflect light, creating a sense of grandeur and elegance. The popularity of Federal architecture can be seen in the construction of government buildings, such as the U.S. Capitol and the White House, as well as in the homes of the wealthy.

Data from the U.S. Department of Commerce indicates that the glass industry in the United States experienced significant growth during the early 19th century. For example, the value of glass production in the United States increased from $1.2 million in 1800 to $6.8 million in 1820. This growth was driven by the development of new glass-making techniques and the expansion of the domestic market.

In conclusion, glass mirrors were widely used in the United States during the Federal period (1789-1829). This era was characterized by a surge in domestic manufacturing, an increase in the middle class, and a preference for Federal architecture, all of which contributed to the popularity of glass mirrors. The growth of the glass industry during this time made it possible to produce large, high-quality mirrors that were both functional and decorative.