Career
Chapin left his hometown to enter the mercantile business in Haverhill, New Hampshire before moving to Chicago in 1832. Following the dissolution of the firm, Chapin joined the Canal Boat Transportation Company. In 1846, Chapin ran for mayor of Chicago as a Whig against Democratic nominee Charles Follansbee and Liberty Party nominee Philo Carpenter, winning the office with just over 55% of the vote.
Following his term as Mayor, Chapin was elected to the city council in 1859.
In 1861, he was nominated by the Union ticket for the office of Commissioner of Public Works. As Chapin was a Republican, he declined the nomination as he felt it was a mischievous move on the part of the Democrats.