His unflagging zeal in promoting road development earned Michigan's first state highway commissioner the nickname "Good Roads" Earle. As a state senator from Detroit in 1901, he headed a committee that developed the first plan for statewide road improvement. He served unofficially and without salary as state highway commissioner from 1903 to 1905, leading the campaign for constitutional amendment to permit the state to participate in the building of public wagon roads. This set the stage for establishment of a state highway department and system. Earle continued officially as commissioner until 1909, the year the world's first mile of concrete was laid on Woodward Avenue in Detroit.