Northwood glass was made by one of the glassmaking companies operated by Harry C. Northwood. His first company, Northwood Glass Co., was founded in Martins Ferry, Ohio, in 1887 and moved to Ellwood City, Pennsylvania, in 1892. The company closed in 1896. Later that same year, Harry Northwood opened the Northwood Co. in Indiana, Pennsylvania. Some pieces made at the Northwood Co. are marked “Northwood” in script. The Northwood Co. became part of a consortium called the National Glass Co. in 1899. Harry left National in 1901 to found the H. Northwood Co. in Wheeling, West Virginia. At the Wheeling factory, Harry Northwood and his brother Carl manufactured pressed and blown tableware and novelties in many colors that are collected today as custard, opalescent, goofus, carnival, and stretch glass. Pieces made between 1905 and about 1915 may have an underlined N trademark. Harry Northwood died in 1919, and the plant closed in 1925.