- Mason & Dulion Co. (1910-1954)
- Mason & Dulion Co., Inc. (1954-1961)
- Mason & Dulion Co. of Alabama (1961-1983
- M&D Mechanical Contractors, Inc. (1977-Present)
1910 to 1920
- In 1910, Mason & Dulion Co. is formed by Leon Edward Dulion and James Edward Mason, two plumbers that had worked together B.F. Barber.
- The first office and shop of the company was located at 4th Avenue and 18th Street North in Birmingham, AL.
- In 1915, an unfortunate hunting accident claimed the life of James Mason. Dulion purchased the widow Mason's interest in the company with the promise that Mason's name would continue with the business.
- In 1916, the office and shop was moved to 4th Avenue and 20th Street in Birmingham.
- During the first decades of the company, plumbing and heating contracts extended to locales as far away as Miami Beach, FL.
1920 to 1950
- During the 1920s, Mason & Dulion Co. worked on the majority of the high rise buildings constructed in Birmingham.
- Dulion's daughter Margaret Louise married Nicholas Rosseau Vance in 1923. Vance joined the company in 1924.
- In 1925, a new shop and office was constructed at 3rd Avenue and 30th Street South in Birmingham. This location would serve as the company's headquarters for 58 years.
- Dulion's son Leon joined the company in 1928.
- Black Friday in 1929 hit Mason & Dulion Co. hard, and the company was forced to declare bankruptcy, as had many other construction companies. In the following years, Dulion repaid all of his creditors; even the over $100,000 the company owed to Crane Co.
- On the onset of World War II, military construction in the South began booming. Leon V. was dispatched to manage projects in Selma, AL; Alexandria, LA; and Mobile, AL.
- In 1945, the Company opened a branch in Pensacola, FL with Leon V. as the manager.
1950 to 1960
- The 1950s brought the birth of air conditioning. In response, the company opened a sheet metal shop at its Birmingham location.
- The company now had three divisions – Plumbing, Heating and Process Piping, and Sheet Metal and Air Conditioning.
- The company was a distributor for Westinghouse Electric HVAC equipment in the early air conditioning years.
- In 1954, the company was incorporated as a Delaware Corporation (Mason & Dulion Co., Inc.). Leon E. Dulion owned 70% interest, Nicholas R. Vance (Dulion's son-in-law) owned 15%, and Leon V. Dulion (Dulion's son) owned 15%.
- In 1954, the company earned its first contract at Redstone Arsenal in Huntsville, AL.
- In 1955, following the deaths of Leon E. Dulion and Nicholas R. Vance, Leon V. Dulion ascended to presidency.
1960 to 1970
- Nicholas R. Vance's widow Margaret D. Vance took over as president of the Alabama company following death of Leon V. Dulion.
- In July of 1961, the company was split into two corporations – Mason & Dulion Co., Inc. of Alabama and Mason & Dulion Co., Inc. of Florida. The Alabama firm would later become M&D Mechanical Contractors and the Florida firm would remain a separate company.
- During the 1960s, the company began to prosper once again, including having landed contracts with 3M in Decatur, AL and the new NASA agency at Redstone Arsenal in Huntsville, AL.
1970 to 1990
- During the 1970s, the company lost its president Margaret D. Vance, who died in 1976. The company also suffered through a period of hard financial times and increased competition from merit shop construction firms.
- In 1977, a new merit shop corporation M&D Mechanical Contractors, Inc. was formed to take advantage of work in the North Alabama area.
- Nicholas D. Vance (Nichoals R. Vance's son) was the sole owner and C.E.O. of both corporations during this time. As the 1970's ended, a new management team was formed.
- By 1978, the company had experienced great growth in the North Alabama area and leased property on Jackson Street in Decatur, AL with the intention of moving the company's headquarters to the city.
- In 1983, the company officially moved the headquarters of the company to an 18,600 square foot office and sheet metal shop that had been built at 1810 Sherman Street Southeast in Decatur, AL.
1990 to Present
- Throughout the 1990s, the company continued to refine its focus and experienced steady growth.
- The company's new services during these years expanded to include specialty piping, vacuum chamber piping, medical gas systems, high-end technical fabrication, and LEED™ certified construction.
- In 2010, the company celebrated its 100th year in businesses with news of record high employment.
- Also in 2010, the company was awarded a five-year contract for the Ares Test Stand and Support Systems being constructed at NASA's Stennis Space Center.
- In 2013, COO Bobby Allfrey was given the ABC of North Alabama's Eagle Lifetime Achievement Award.