Thompson River (Missouri)
| Thompson River Thompson Fork Grand River | |
|---|---|
| Location | |
| Country | United States |
| State | Iowa, Missouri |
| Physical characteristics | |
| Source | Near Greenfield |
| • location | Adair County, Iowa |
| • coordinates | 41°21′24″N 94°25′52″W / 41.35667°N 94.43111°W |
| • elevation | 1,360 ft (410 m) |
| Mouth | Grand River |
• location | Livingston County, Missouri |
• coordinates | 39°45′50″N 93°36′52″W / 39.76389°N 93.61444°W |
• elevation | 679 ft (207 m) |
| Length | 188 mi (303 km) |
| Basin size | 1,850 sq mi (4,800 km2) |
| Discharge | |
| • location | Trenton, 25.2 miles (40.6 km) from the mouth |
| • average | 1,059 cu ft/s (30.0 m3/s) |
| • minimum | 1 cu ft/s (0.028 m3/s) |
| • maximum | 95,000 cu ft/s (2,700 m3/s) |
| Basin features | |
| Tributaries | |
| • left | Weldon River, Honey Creek |
| • right | Sugar Creek, Hickory Creek |
The Thompson River is the largest tributary of the Grand River in the central United States, flowing from southern Iowa into Missouri. In Iowa, it is known simply as the Grand River and passes near the city of Grand River. The river is 188 miles (303 km) long, and its drainage basin is roughly 1,850 square miles (4,800 km2), of which 1,111 square miles (2,880 km2) are in Missouri.
It rises in the agricultural lands of Adair County, Iowa, a few miles northeast of Greenfield. The river initially flows east then bends south, passing Macksburg and Davis City and crossing Interstate 35. It then flows into Missouri, where much of its course is channelized. The Weldon River joins at the town of Trenton, the largest settlement along the Thompson River. Below Trenton, the Thompson meanders south for another 25 miles (40 km), joining the Grand River just north of Utica in Livingston County.