“There were a lot of myths and rumors saying that’s what happened here in Missoula,” Dixon said. “When we started the project, we wondered if that was the end-all, be-all explanation. We found out it wasn’t the case.”

At least in most instances, the team noted.

The Penwell Hotel, built in 1910 on the corner of Higgins Avenue and South Third Street West, opened the boom of commercial expansion on the south side of the Clark Fork River.

When the Higgins Avenue Bridge was installed, builders raised the grade south of the river, turning the Penwell’s main floor into a basement. The team found one similar example, though it has yet to be verified with documentation.

Manning, who has spent hours searching through records held at the Mansfield Library, notes a 1958 article in the Missoulian recalling a Chinese restaurant that once fronted a ravine north of the river. The ravine was filled in during efforts to flatten the downtown area, sometime around 1886.

The restaurant became a basement, part of which may still exist. But Manning and Dixon aren’t so quick to extend similar conclusions to other parts of the city.