Founded in 1910, M&D Mechanical Contractors, Inc. is one of the few companies that can say it not only survived the Great Depression, recessions, and changes within the industrial community, but can also say it left an indelible mark on the world around it. Originally founded as Mason & Dulion Co., the company was instrumental in the construction of many of the high-rise buildings in downtown Birmingham in the 1920s and later supported war efforts through projects at the Pensacola Naval Air Station, Eglin Field, and other military installations. During the time of early space exploration, the company worked with NASA at the Marshall Space Flight Center on many projects, including the Saturn C-5 Test Stand Support Systems.

Today, M&D provides mechanical contracting services and solutions to clients within the industrial, institutional, commercial, and government sectors primarily in North Alabama, as well as other locations throughout the southeast. In more recent years, the company has added specialty services to its capabilities including medical gases, duct fabrication, and green building. The company has in-house CAD and Building Information Modeling (BIM) capabilities and fabricates piping and custom metal products, including spiral and ready-to-erect duct work, in its cutting-edge pipe and metal fabrication shops.

M&D Mechanical has earned a reputation for safety and quality. The company has an excellent safety record and has received numerous safety awards, including the ABC STEP Award. Additionally, M&D Mechanical invests in its employees through training programs, both in-house and through North Alabama Craft Training Foundation, the Tennessee Valley Training Center, and the Gulf Coast Safety Council. This influence on training has allowed the company to develop a strong technical capability among its employees.