| Unit Pref: | Imperial |
| Settlement Type: | Township |
| Official Name: | Seneca Township |
| Subdivision Type: | Country |
| Subdivision Name: | United States |
| Subdivision Type1: | State |
| Subdivision Name1: | Illinois |
| Subdivision Type2: | County |
| Subdivision Name2: | McHenry |
| Leader Title: | Supervisor |
| Established Title: | Established |
| Established Date: | November 6, 1849 |
| Area Total Sq Mi: | 35.96 |
| Area Land Sq Mi: | 35.95 |
| Area Water Sq Mi: | 0.01 |
| Area Water Percent: | 0.03 |
| Population As Of: | 2020 |
| Population Total: | 2893 |
| Population Density Sq Mi: | 81.9 |
| Utc Offset: | -6 |
| Timezone Dst: | CDT |
| Utc Offset Dst: | -5 |
| Website: | http://www.senecatownship.com/ |
| Blank Name: | FIPS code |
| Blank Info: | 17-111-68653 |
Seneca Township is located in McHenry County, Illinois. As of the 2020 census, its population was 2,893 and it contained 1,102 housing units.
According to the 2010 census, the township has a total area of, of which (or 99.97%) is land and (or 0.03%) is water.[1]