| S. J. Chadbourne | |
| Office: | Secretary of State of Maine |
| Term Start: | 1876 |
| Term End: | 1878 |
| Term2: | 1880 |
| Governor: | Seldon Connor |
| Predecessor: | Sidney Perham |
| Successor: | Edward H. Gove |
| Governor2: | Daniel F. Davis |
| Predecessor2: | Edward H. Gove |
| Successor2: | Joseph O. Smith |
| Birth Date: | 28 July 1830 |
| Birth Place: | Dixmont, Maine, U.S. |
| Death Place: | Augusta, Maine, U.S. |
| Party: | Democratic (until 1880) Republican (1880) |
Sumner John Chadbourne (July 28, 1830 – October 1, 1902) was an American politician in the state of Maine. He served as Secretary of State of Maine from 1876 to 1878, and in 1880. He also served in the Maine House of Representatives.[1] [2]