Rising in the Cascades and flowing westward, the Calapooia River is a tributary of the Willamette River. It passes Crawfordsville and Brownsville before its confluence with the Willamette at Albany.

Like several other Oregon places, the river derives its names from the Calapooya Indians who were indigenous to the Willamette Valley when the first white settlers arrived. It appears to be the only case in which the name was spelled without the "y"