Oliver Barrett Clason was born in Gardiner, Maine on September 28, 1850.
He was educated at public schools in Gardiner and graduated from Bates College in the class of 1877 to be remembered by his classmates as a corpulent, fun-loving man who was never at a loss for words.
For the next three years he taught school in Maine and Massachusetts before deciding on a career as a lawyer. He studied law with Judge Henry S. Webster in Gardiner and was admitted to the bar in October 1881.
Practicing law in Gardiner for the remainder of his career, he formed a partnership in 1885 with future Senate President and Justice of the Maine Supreme Judicial Court, Albert M. Spear.
His first political office consisted of two terms in the Maine House of Representatives serving from 1889 to 1892.
From 1894 to 1896 he was Mayor of the City of Gardiner and in the latter two years a member of the Executive Council as well.
Elected to the Maine Senate in 1897 and again in 1899 he served as that body’s President in his second term.