From the record
“The Belknap Bridge crosses the McKenzie River near the unincorporated community of Rainbow in Lane County, Oregon, United States. It is approximately three miles west of the town of McKenzie Bridge which is named after the bridge.”
Wikipedia article Belknap Bridge, CC BY-SA 4.0.
One of 123 National Register listings published here for Lane County · listed in 1979 · category: Structure.
Sources: the Wikipedia article · the case file at the National Archives · the National Register database, National Park Service