Allen was born in Lynn, Massachusetts, on October 6, 1874. A businessman and executive with the Winslow Brothers & Smith Company from 1893, he rose to become the company's president from 1912 to 1929, and was married to Clara Winslow in 1897.
He entered public service as a member of the Norwood, Massachusetts, Board of Assessors from 1910 to 1915 and as a Norwood Town Selectman from 1915 to 1922. During that period, he also served in the Massachusetts House of Representatives from 1918 to 1919, and in the Massachusetts Senate from 1921 to 1924. In 1924, he was elected Lieutenant Governor of Massachusetts and served with fellow Republican Governor Alvan T. Fuller from 1925 to 1929, when he succeeded Fuller as Governor, and served until 1931.
During the administration of Governor Allen, he established the Massachusetts Transit Authority, the Massachusetts Port Authority, and the state's Industrial Commission. He expanded facilities to care for the sick and the indigent, and in an unusual move for the times, appointed two women to judgeships in Massachusetts.
In 1930, Governor Allen was defeated for re-election by Democrat Joseph B. Ely, and returned to the Winslow Brothers & Smith Company, where he served as Chairman of the Board until his death.
Governor Allen died on October 5, 1950, and is buried in Highland Cemetery in Norwood, Massachusetts.
Allen was born in Jacksonville, Florida, USA, and graduated from Friends High School (now Sidwell Friends) in Washington, D.C. He also graduated from the Cumberland School of Law in Lebanon, Tennessee in 1931 and was admitted to the Tennessee bar the same year.
Allen was seen by some as the representative of the urban and progressive forces as opposed to those whose support was largely rural, such as Clement.
Allen soon became the leading figure of the convention, and its proposal, which called for an assessment of 25% of appraised value on residential and agricultural property and 40% on commercial property, was essentially Allen's plan, and was subsequently approved by Tennessee voters and remains the law as of 2005.