MACTEC was among the largest engineering design companies in the United States. The company provided engineering, environmental, and construction services to private- and public-sector clients. MACTEC was based in Denver, Colorado until 2002, when they merged with LAW Engineering and the headquarters were moved to Alpharetta, Georgia. At that time they employed 3100 staff in 80 locations, with capability in more than 50 scientific and engineering disciplines.