Bowerman entered Willamette University in 1893, and graduated with a law degree in 1896.
He received his early education in public schools and moved to Salem, Oregon in 1893. He was admitted to the Oregon Bar the following year, practicing law in Salem until 1899. He then moved to Condon, in Gilliam County, Oregon, where he lived for the next 12 years.
Bowerman's service in the Spanish–American War briefly interrupted his practice of law. Bowerman was a Republican. He was elected to the Oregon State Senate from Gilliam County in 1904 and was reelected four years later.
He served as president of that body from 1909 to 1911. When Governor Frank W. Benson was incapacitated by ill health in June 1910, he asked Bowerman, as president of the Senate, to assume gubernatorial responsibilities. On June 16, 1910, at age thirty-three, Bowerman became Acting Governor.
Mindful of the bureaucratic economy, Bowerman advocated the establishment of a Board of Control to administer the state institutions, which would permit fiscal savings by combined purchasing for state institutions through the office of a single purchasing agent. However, the Board of Control was not established until the administration of his successor. He acted to reduce the risk of loss through bank failure by prohibiting Oregon bankers from the use of speculative stock as assets if they had actively promoted that stock.
Establishment Republicans, unwilling to relinquish party control over nominations, held an "assembly" in 1910 at which they nominated Bowerman as their candidate for governor. Bowerman campaigned on a platform supporting modernized highway systems, increased economies in the administration of government, and continued tight control of state land management. Bowerman was also involved in a sex scandal, having an affair with his secretary.
West defeated him 54,853 votes to 48,751. After leaving the office of governor on January 8, 1911, Bowerman moved to Portland, where he resumed the practice of law. He was reelected president of the State Senate but retired following the 1911 session.
As a private citizen he actively supported Oregon's first statewide bond issue for highway construction, a $6,000,000 proposal. He also served as an active lobbyist for years at the State Legislature. Bowerman died in Portland in 1957, and was buried in Lincoln Memorial Park in Portland, Oregon.
In 1904, the citizens of Oregon adopted a direct primary law prohibiting party nominating conventions.