马瑟尔谢尔河是密苏里河支流，自位于蒙大拿州马丁斯代尔附近的南北汇流处至流入密苏里河有550.2千米长。算上汇流处之前的支流则有684–800千米长。

The Musselshell River is a tributary of the Missouri River, 341.9 miles (550.2 km) long from its origins at the confluence of its North and South Forks near Martinsdale, Montana to its mouth on the Missouri River. It is located east of the Continental divide entirely within Montana in the United States. Counting its pre-confluence tributaries, it measures 425–500 miles (684–805 km) in length.