John D. Lynch, a mayor of Cambridge for three terms, died yesterday at the age of 80. A self-made millionaire who served on the City Council until he was 78, Lynch had been active in Cambridge politics for more than 30 years.

For much of that time, the northwest part of Cambridge, between Porter Sq. and Arlington, was known as "Lynchville" because of his influence. Lynch began his political career in 1930 by winning election to the City's School Board, and in 1936 and 1937, under Cambridge's Plan B charter, he was twice elected mayor.

In 1941, when the City changed to its present Plan B charter, Lynch won a seat on the City Council, where he remained for 19 years. His fellow Councillors elected him mayor again in 1946.

Lynch became wealthy as a result of the drugstore and the drugstore that he ran, both in North Cambridge. It was a source of pride with him that investors in his bank never lost a penny during the Depression.

Cambridge Mayor Edward A. Crane '35 said last night that the City had lost "a good and devoted public servant." Crane called Lynch "a wonderful citizen and a very unusual one," and recalled that "he never liked to leave Cambridge. Whenever he got as far as East Arlington, he'd be homesick."

Lynch is survived by his brother and two sisters. Funeral rites will be held Friday at his home at 20 Arlington St.