| Official Name: | Decatur Township Marion County |
| Settlement Type: | Township |
| Mapsize: | 250px |
| Subdivision Type: | Country |
| Subdivision Name: | United States |
| Subdivision Type1: | State |
| Subdivision Name1: | Indiana |
| Subdivision Type2: | County |
| Subdivision Name2: | Marion |
| Government Type: | Indiana township |
| Named For: | Stephen Decatur |
| Area Total Km2: | 83.9 |
| Area Land Km2: | 83.7 |
| Area Water Km2: | 0.2 |
| Area Total Sq Mi: | 32.4 |
| Area Land Sq Mi: | 32.3 |
| Area Water Sq Mi: | 0.1 |
| Population As Of: | 2020 |
| Population Total: | 36951 |
| Population Density Km2: | auto |
| Timezone: | Eastern (EST) |
| Utc Offset: | -5 |
| Timezone Dst: | EDT |
| Utc Offset Dst: | -4 |
| Elevation M: | 234 |
| Elevation Ft: | 768 |
| Blank Name: | FIPS code |
| Blank Info: | 18-17092[1] |
| Blank1 Name: | GNIS feature ID |
| Blank1 Info: | 0453255[2] |
Decatur Township is one of the nine townships in Marion County, Indiana, United States, and part of the consolidated city of Indianapolis. As of the 2020 census, it had a population of 36,951.[3] Located in the southwest corner of the county, the township is home to the Indianapolis International Airport main terminal. It is one of the most rural sections of the county, but has seen many new residential and commercial developments. AmeriPlex, one of the largest industrial parks in Indiana, is in Decatur Township. Through the White River, Decatur and Perry townships share the only water boundary among Marion County's townships.
The township was settled in the 1820s by mostly Quakers from South Carolina. They settled along the banks of the White River. West Newton is a small Quaker-settled town inside the township. Many of today's residents can trace their lineages back to these early settlers.
Decatur Township was named for Stephen Decatur.[4]
The township is the home of the Decatur Township Civic Council[5] and the Metropolitan School District of Decatur Township.[6] The Indianapolis Challenger Center calls Decatur Township home.
Camby (also sometimes called "West Union Station") is a neighborhood in western Decatur Township that also extends into neighboring Hendricks and Morgan counties, centered along Camby Road near State Road 67.[7] Its elevation is above sea level, and it is located at 39.6625°N -86.3167°W (39.6625457, −86.3166582).[8] Camby has a post office with the ZIP Code of 46113.[9]
Decatur Township was home to 24,726 residents in the 2000 census. As of the 2010 census, the population had increased to 32,388.[10] By the 2020 census it had reached 36,951.[11] The almost 50% increase between 2000 and 2020 census tabulations ranks Decatur Township second among Marion County's nine townships for population growth.