Ryan Hydroelectric Facility, Ryan-to-Rainbow 100 kV Transmission Line, West bank of Missouri River, northeast of Great Falls, Great Falls, Cascade County, MT

Significance: The transmission line is an early and well preserved example of an important innovation in electric power transmission line technology, the H-frame support structure. Comprised of two-wood poles connected by a cross-arm(s), the H-frame offered a viable and comparatively economical means for the construction of transmission lines of over 66,000 volts. It became the standard for high voltage line construction following its introduction in the mid-1910s, and remained so for decades.

Survey number: HAER MT-98-C

Building/structure dates: 1915 Initial Construction

power industry electric lines electric utilities utility poles great falls ryan transmission line kv transmission line bank west bank missouri river northeast great falls cascade cascade county montana historic american engineering record photo ryan hydroelectric facility ultra high resolution high resolution power lines electric power library of congress

1969 - 1980

Library of Congress

http://www.loc.gov/

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