Mormon Settlement and the Renaming to Idaho Falls

The railroaders who built Eagle Rock were transient workers. The people who planted the place permanently into the soil were Latter-day Saint settlers who poured into the upper Snake River Valley beginning in the eighteen seventies and accelerating sharply through the eighties and nineties. Brigham Young had sent colonizing parties into southeastern Idaho as early as eighteen sixty, and the completion of the Utah and Northern Railway made the Snake River Plain newly accessible. Mormon settlers, skilled at cooperative irrigation from their Utah experience, looked at the volcanic plain surrounding Eagle Rock and saw not a wasteland but a blank canvas.

The key was water. The Snake River carried an enormous volume, but the benchlands above the river were dry. Beginning in the eighteen eighties, cooperative canal companies, many organized along church ward lines, began digging diversion ditches from the Snake to the surrounding farmland. By the turn of the twentieth century, hundreds of thousands of acres that had been sagebrush desert were growing potatoes, wheat, and sugar beets.

As the agricultural community stabilized and the railroad's influence was absorbed into the broader economy, the old frontier name Eagle Rock began to feel out of place. In eighteen ninety-one the town was renamed Idaho Falls, after the natural cascade in the Snake River that had given the original crossing its character. The name carried a booster's optimism: it sounded like a destination, a place with a feature worth seeing, not just a railroad utility stop.

Latter-day Saint influence remained deep. The Idaho Falls Idaho Temple, dedicated in nineteen forty-five, was the first temple built in Idaho, and its white spire rising above the river became the visual signature of the city. When visitors picture Idaho Falls today, they are almost always picturing that temple reflected in the Snake.