JOHN SLETTEN, a carpenter from Montana, began a partnership with an accountant and formed Kleppe Sletten Construction. Soon after, Kleppe retired and the company was renamed John Sletten Construction.

The very first office was held in the basement of the Slettens home in Great Falls, MT, performing light commercial construction and remodel work.

Sletten Construction joint ventured to build its first major project, the Butte High School in Butte, MT. A few years later, the company moved from the Slettens basement to 1301 10th Ave. N, Great Falls, MT, which became the office, shop and storage yard. For the next 45-years, this location was the company headquarters building.