| St. Jacob Township | |
| Settlement Type: | Township |
| Image Map1: | Illinois in United States (US48).svg |
| Map Caption1: | Location of Illinois in the United States |
| Coordinates: | 38.6967°N -89.7678°W |
| Subdivision Type: | Country |
| Subdivision Name: | United States |
| Subdivision Type1: | State |
| Subdivision Name1: | Illinois |
| Subdivision Type2: | County |
| Subdivision Name2: | Madison |
| Established Title: | Settled |
| Established Date: | November 2, 1875 |
| Leader Title: | Mayor |
| Leader Title1: | Supervisor |
| Unit Pref: | Imperial |
| Area Total Sq Mi: | 35.95 |
| Area Land Sq Mi: | 35.6 |
| Area Water Sq Mi: | 0.35 |
| Elevation Ft: | 512 |
| Population As Of: | 2010 |
| Pop Est As Of: | 2016 |
| Pop Est Footnotes: | [1] |
| Population Est: | 2684 |
| Population Density Sq Mi: | 72.4 |
| Timezone1: | CST |
| Utc Offset1: | -6 |
| Timezone1 Dst: | CDT |
| Utc Offset1 Dst: | -5 |
| Blank Name: | FIPS code |
| Blank Info: | 17-119-66872 |
| Blank2 Name Sec2: | Wikimedia Commons |
St. Jacob Township is located in Madison County, Illinois, in the United States. As of the 2010 census, its population was 2,578 and it contained 981 housing units.[2]
According to the 2010 census, the township has a total area of, of which (or 99.03%) is land and (or 0.97%) is water.[2]