| Official Name: | Casner Township |
| Settlement Type: | Township |
| Image Map1: | Map of Illinois highlighting Jefferson County.svg |
| Mapsize1: | 150px |
| Map Caption1: | Jefferson County's location in Illinois |
| Subdivision Type: | Country |
| Subdivision Name: | United States |
| Subdivision Type1: | State |
| Subdivision Name1: | Illinois |
| Subdivision Type2: | County |
| Subdivision Name2: | Jefferson |
| Area Total Sq Mi: | 36.02 |
| Area Land Sq Mi: | 35.98 |
| Area Water Sq Mi: | 0.04 |
| Area Water Percent: | 0.11 |
| Population As Of: | 2010 |
| Population Density Sq Mi: | 34.4 |
| Elevation M: | 151 |
| Elevation Ft: | 495 |
| Coordinates: | 38.35°N -94°W |
| Timezone: | CST |
| Utc Offset: | -6 |
| Timezone Dst: | CDT |
| Utc Offset Dst: | -5 |
| Postal Code Type: | ZIP codes |
| Postal Code: | 62801, 62808, 62864, 62877, 62894, 62898 |
| Blank Name: | FIPS code |
| Blank Info: | 17-081-11670 |
| Pop Est As Of: | 2016 |
| Pop Est Footnotes: | [1] |
| Population Est: | 1233 |
| Unit Pref: | Imperial |
Casner Township is one of sixteen townships in Jefferson County, Illinois, USA. As of the 2010 census, its population was 1,239 and it contained 510 housing units.[2]
According to the 2010 census, the township has a total area of, of which (or 99.89%) is land and (or 0.11%) is water.[2] The township is centered at 38°21'N 89°5'W (38.349,-89.088). It is traversed east–west by Interstate Route 64 and State Route 15.
(This list is based on USGS data and may include former settlements.)
The township contains these three cemeteries: Locust Grove, Mount Catherine and Randolph.