United States Glass Company was formed in 1891 from 18 different companies that had plants/factories in Ohio, Pennsylvania, Indiana, and West Virginia. The merger was made more difficult because of communications issues across four states. Two new factories were built in Indiana and Ohio in the 1930s and they produced pressed glass and fine stemware. The older factories also produced depression glass including stretch glass, amberina, and carnival glass. US Glass produced a range of glass, including fine crystal pieces as well as lower quality glass. They were known for the wide range of colored glass, including medium blue, yellow, green, clear, brown, amber, and black.
Over the years, the factories were forced out of business by fires, strikes and the economy. By 1950, the only remaining plant was the one in Tiffin, Ohio and all the glass began to be stamped with the Tiffin name. However, it continued to go by the United States Glass Company name until it went bankrupt in 1963. At that time, the company was reorganized as the Tiffin Art Glass Company.
In 1979, the company was sold to Towle Silversmiths and became a subsidiary named Tiffin Crystal. Towle continued to sell the stemware until 1990 via mail order.
Sources: Pamela Wiggins, “United States Glass Co.: Marks, Patterns and Wares”
https://www.thesprucecrafts.com/united-states-glass-co-148700
https://www.tiffinglass.org/the-history-of-tiffin-glass