- elevation 679 ft (207 m) Length 303 km Basin area 4,791 km² | - elevation 1,360 ft (415 m) - average 1,059 cu ft/s (30 m/s) Discharge 29.99 m³/s Basin area 4,791 km² | |
- location | ||
The Thompson River is the largest tributary of the Grand River in the central United States, flowing from southern Iowa into Missouri. 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.
Map of Thompson River, Jackson Township, MO, USA
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.