- Location: Jefferson County, Missouri
- Legal status: Third-class city
- Population: 19,965 (Change since 1990: +6.0%)
- Name origin: George Arnold
- Located along I-55 and US 61/67 at the south bank of Meramec River
- Latitude: 38°25'58" N (+38.4328)
- Longitude: 90°22'39" W (-90.3775)
- Civil township: Arnold
- Land area: 11.2 square miles
- Water area: 0.33 square miles (213.7 acres)
As the crow flies, Arnold is...
Name origin
Named for George Arnold, landowner
Timeline
- Sep. 18, 1972
- Arnold incorporated as a 3rd class city, encompassing Beck, Flamm City, Maxville, and Ten Brook
- Beck (Merged with Arnold)
- Neighborhood located around the intersection of US 61/US 67 and Richardson Road
- Latitude & Longitude: 38°24'42" N, 90°22'58" W
- Name origin: Named for Emmanual Beck, a local farmer
- Flamm City (Merged with Arnold)
- Located along Telegraph Road (MO 231)
- Latitude & Longitude: 38°25'01" N, 90°21'24" W
- USGS Quad: Oakville
- Maxville (Merged with Arnold)
- Located in the vicinity of Missouri State Road (Old MO 141) and Old Lemay Ferry Road on
the west side of I-55
- Latitude & Longitude: 38°26'11" N, 90°23'19" W
- Elevation: 578
- USGS Quad: Maxville
- Name origin: Named for Max Stengel, first business owner
- Ten Brook (Merged with Arnold)
- Located along Arnold Tenbrook Road near the Frisco Railroad tracks
and Meramec River
- Latitude & Longitude: 38°26'01" N, 90°20'60" W
- USGS Quad: Oakville
- Name origin: Named for John Ten Brook, landowner
| Year | Population | Percent change |
|---|
| 1980 | 19,141 | -- |
| 1990 | 18,828 | -1.6% |
| 2000 | 19,965 | +6.0% |