The East Gallatin River flows 42 miles (68 km) in a northwesterly direction through the Gallatin valley, Gallatin County, Montana. Rising from the confluence of Rocky Creek and several other small streams, the East Gallatin begins about one mile (1.6 km) east of downtown Bozeman, Montana. The river joins the main stem of the Gallatin River 2.3 miles (3.7 km) north of Manhattan, Montana.