Young Leavitt studied civil engineering, and early in his career was contracted by John Roebling, the builder of the Brooklyn Bridge, to survey a large tract of land.
Having gained some measure of confidence in his abilities, Leavitt struck out for the west in 1854, reaching Dubuque, Iowa, where he remained for less than a year before settling at Waterloo, Iowa. While in Dubuque, Leavitt married Caroline Clark Ware of Granville, Illinois. Shortly after his move to Waterloo, the young engineer decided on a change of career, and became a banker.
Within a decade he founded his own private banking firm.
Several years later, on the admission of a new partner, the sole proprietorship of Leavitt"s bank necessitated a change of name to Leavitt & Lusch. Subsequently, on the addition of another partner, the bank became known as Leavitt, Johnson & Lusch.
John Hooker Leavitt worked at the firm for 50 years, during the various permutations of the corporation"s name. He served as president of the institution, located at Commercial and Fourth Streets in downtown Waterloo, until 1901.
A staunch Republican, Leavitt served only one term in the Iowa State Senate.
He was an early benefactor of Talladega College, Alabama"s oldest historically black college, and in 1903 he joined the Pocumtuck Valley Memorial Association in Deerfield, Massachusetts, where his father Roger Hooker Leavitt had served as vice president Leavitt"s brother William also lived in Waterloo, but eventually relocated to Minneapolis, Minnesota. Honorary Colonel Roger Hooker Leavitt"s body was returned to Charlemont, Massachusetts, longtime home of the family, for burial.
John Hooker Leavitt died at Waterloo in 1906.
In 1871, Leavitt was elected to the Iowa Senate, where he was engaged in the fight to prevent the return of James Harlan to the United States Senate after his service as a member of Abraham Lincoln"s cabinet.