Company Story
1874 - Edward A. Calahan founded American District Telegraph Company, the precursor to ADT Inc.
1901 - The company was officially renamed American District Telegraph Company of New York.
1925 - The company began to expand nationally, establishing operations in Chicago, Philadelphia, and Baltimore.
1962 - The company changed its name to ADT Security Systems, Inc.
1983 - ADT was acquired by the conglomerate Tyco International.
2012 - Tyco International spun off its flow control business, and ADT became an independent company.
2016 - ADT acquired Protectron, a Canadian security company.
2020 - ADT acquired Defenders, a leading security dealer in the United States.