This collection is a subgroup (Division) of the Montana Public Service Commission records, RS 501. The Utility Division is now, as of 2025, named the Regulatory Division. Please see the primary finding aid for more Montana Public Service Commission records.

These records consist predominantly of annual reports (1914-1986) made by electric utility companies, gas companies, heating utility companies, water companies, telegraph companies, telephone companies, and pipeline companies to the Montana Public Service Commission. The reports include a vast amount of data on the history, financing, corporate ownership, physical plants, and production. Many of the reports are accompanied by rate schedules and regulations. Some of the reports are copies of the reports made to the Federal Power Commission and do not directly reflect their Montana operations.

In addition there are accident reports (1957-1966) for electric, gas, and telephone utilities; appraisal reports (1919-1927) for several electric utilities; and other reports (1922-1953) for several water companies.