The Glass, Molders, Pottery, Plastics and Allied Workers International Union (GMPIU) was a labor union representing craft and industrial workers primarily in the ceramics, china, craft metals, fiberglass, glass, insulation, and pottery industries, in the United States and Canada.

[3][4] The Coopers' International Union of North America followed in 1992.

[3][5] With the Coopers merger, the GMPIU had about 80,000 members in the United States and Canada in about 435 locals.

[6] The Great Recession cut heavily into its membership, and by the end of 2012 it had just under 28,000 members.

[7] The merger was completed on January 1, 2018, and the union became the GMP Council of the Steelworkers.