First, though it is probably not unique in this sense, the Bear River flows through three states, Utah, Wyoming, and Idaho. It starts in Utah, winds into Wyoming, drifts back into Utah, then into Wyoming again, before entering Idaho. The longest stretch of the river is in Idaho, looping up past Montpelier to Soda Springs, then plunging down and back into Utah, where it flows into the Great Salt Lake.
That’s where its one, true superlative comes from. The Bear River is the largest river in the United States whose waters never reach an ocean. The outflow of the river is less than 100 miles from where it began, but the water journeys some 350 miles to get there.
It wasn’t always so. The Bear River once—geologically once—flowed into the Snake River like most other respectable streams in southern Idaho. Lava flows that occurred long before you were born—maybe before anyone was born—diverted the flow south from Soda Springs.