| Official Name: | Old Jamestown, Missouri |
| Settlement Type: | Unincorporated community Census-designated place |
| Mapsize: | 250x200px |
| Pushpin Label Position: | right |
| Subdivision Type: | Country |
| Subdivision Name: | United States |
| Subdivision Type1: | State |
| Subdivision Name1: | Missouri |
| Subdivision Type2: | County |
| Subdivision Name2: | St. Louis |
| Established Date: | 2010 |
| Unit Pref: | Imperial |
| Area Footnotes: | [1] |
| Area Total Km2: | 38.73 |
| Area Land Km2: | 38.71 |
| Area Water Km2: | 0.02 |
| Area Total Sq Mi: | 14.96 |
| Area Land Sq Mi: | 14.95 |
| Area Water Sq Mi: | 0.01 |
| Population As Of: | 2020 |
| Population Total: | 19790 |
| Population Density Km2: | 511.23 |
| Population Density Sq Mi: | 1324.10 |
| Timezone: | Central (CST) |
| Utc Offset: | -6 |
| Timezone Dst: | CDT |
| Utc Offset Dst: | -5 |
| Elevation Ft: | 538 |
| Coordinates: | 38.8392°N -90.2819°W |
| Postal Code: | 63034 |
| Area Code: | 314 |
| Blank Name: | FIPS code |
| Blank Info: | 29-54352[2] |
| Blank1 Name: | GNIS feature ID |
| Blank1 Info: | 2583784 |
| Website: | http://www.oldjamestownassn.org |
Old Jamestown is an unincorporated community and census-designated place (CDP) in St. Louis County, Missouri, United States. The population was 19,184 at the 2010 census.[3] Old Jamestown is northwest of the city of St. Louis and borders the Missouri River.
According to the United States Census Bureau, the CDP has a total area of 38.7sqkm, of which 0.02sqkm, or 0.06%, is water.[3] The community is located mostly to the north and west of U.S. Route 67 in northern St. Louis County. West Alton is to the north, across the Missouri River. Florissant is to the southwest, and Black Jack and Spanish Lake are to the south. The CDP is located north of downtown St. Louis.
Old Jamestown first appeared as a census designated place in the 2010 U.S. Census.
| White alone (NH) | 7,928 | style='background: #ffffe6; | 4,832 | 41.33% | style='background: #ffffe6; | 24.42% | |
| Black or African American alone (NH) | 10,253 | style='background: #ffffe6; | 13,531 | 53.45% | style='background: #ffffe6; | 68.37% | |
| Native American or Alaska Native alone (NH) | 23 | style='background: #ffffe6; | 26 | 0.12% | style='background: #ffffe6; | 0.13% | |
| Asian alone (NH) | 336 | style='background: #ffffe6; | 307 | 1.75% | style='background: #ffffe6; | 1.55% | |
| Pacific Islander alone (NH) | 11 | style='background: #ffffe6; | 3 | 0.06% | style='background: #ffffe6; | 0.02% | |
| Other race alone (NH) | 34 | style='background: #ffffe6; | 132 | 0.18% | style='background: #ffffe6; | 0.67% | |
| Mixed race or Multiracial (NH) | 324 | style='background: #ffffe6; | 636 | 1.69% | style='background: #ffffe6; | 3.21% | |
| Hispanic or Latino (any race) | 275 | style='background: #ffffe6; | 323 | 1.43% | style='background: #ffffe6; | 1.63% | |
| Total | 19,184 | style='background: #ffffe6; | 19,790 | 100.00% | style='background: #ffffe6; | 100.00% |