Sunbury Township, formed in 1808, contained the present townships of Harlem, Trenton, Porter, half of Berkshire and half of Genoa as well as Morrow County's Peru, Bennington, Lincoln and Harmony Townships. Slowly the different townships were set off with Genoa being the last to pull off from Sunbury.
Sometime between 1830 and 1835, the name was changed to distinguish the township from the Village of Sunbury in Berkshire Township. Mr. Gilbert Van Dorn suggested the name for his native state capital, Trenton, New Jersey.
Early settlers included John Culver, Michael Ely, John Williamson, John Ginn, William Ridgeway, Mr. Pensing, James and Owen Hough, Gilbert Van Dorn, Oliver Gratax, Ira Pierson, Jonathon and Lavin 0. Condit, Smith Conit, Lyman Hendricks, Mr. Roberts, William Perfect, A.C. Leak, Mordecai Thomas, Bartholomew Anderson, Pearson Spinning and George Akerson. They came from New Jersey, Pennsylvania, New York, Delaware and Kentucky.
The three communities of North Condit, Condit Station and South Condit are the township's closest things to towns.