According to legend, the town and the creek got their name from the muleskinner "Big Sandy" Lane. The creek was flooded during one of his long treks from Cow Island to Fort Benton. When "Big Sandy" fluently bewailed his bad luck in superlatives reserved strictly for "skinners," the creek dried up immediately and he was able to cross! Probably a more correct version of the legend was he lost a wheel at the crossing and setup camp. Since then the creek and the camp were called Big Sandy. Regardless of origin, the campsite and crossing were used by the Cow Island and Fort Walsh Trails.
While Fort Assiniboine was being built in 1879, McNamara and Marlow erected a warehouse at the trail crossing. It was not until 1886 that Swanson constructed the first commercial establishment, a saloon in a tent. The town was born, with a boxcar for a depot and a one-room shack for the section foreman. The rest of the town consisted of the M&M warehouse and nine saloons, mostly tents on wooden platforms. After a few hours at the bar, the nightly sport was to hook onto the platforms with horses, and pull the saloons wildly across the prairie with tent flaps flying. In hot pursuit were the bar owners, yelling and swearing! It was a rip-roaring town, filled nightly with gandy dancers, cowboys, Indians, soldiers and hopefully nine saloons that provided
the only entertainment.