Capt. John Mullan considered the pass as a crossing point for his road in 1858, but decided on a northern route instead. A $50,000 federal appropriation improved the pack trail across the pass a few years later.
Chief Joseph used the pass in evading pursuing troops during the Flight of the Nez Perce.
Lolo Pass seemed a natural route for a railroad connecting Montana with points west, and there was talk of one coming through for years. A railroad survey team did some preliminary work there in about 1900, improving a wagon road, but the idea of tracks across the mountain was abandoned.
In 1912 the federal government spent close to a quarter million dollars improving a 23-mile stretch through the canyon to better service the Powell and Lochsa ranger stations. In 1935 about 150 prisoners from the federal penitentiary at Leavenworth showed up to work on the road, and during World War II some of the Japanese “evacuees” from the West Coast did road work.
But it wasn’t until 1962 that the dream of following Lewis and Clark across Idaho in an automobile finally came true.
It was a watershed event for the region, so politicians showed up to celebrate the opening of the pass, as did hundreds of residents from both sides of the border. Ribbon cutting ceremonies are as boring as watching grass grow, so someone cooked up a twist: the governors of Idaho and Montana would push and pull a crosscut saw through a small log to dedicate the opening of US Highway 12, which runs from Aberdeen, Washington to Detroit, Michigan.