McMaster-Carr Supply Company is a private American supplier of hardware, tools, raw materials, industrial materials, and maintenance equipment. They function as a business-to-business company. The company was founded in 1901 and is based in Elmhurst, Illinois, with distribution centers in Robbinsville Township, New Jersey; Santa Fe Springs, California; Douglasville, Georgia and Aurora, Ohio. A new distribution center and regional headquarters began construction in June 2025 in Fort Worth, Texas, with completion expected in 2027.