The previous dual radar sites under the NSF Mid-Sized Infrastrucure (MSI) program were built at Fort Hays (Kansas, 2009), Christmas Valley (Oregon, 2010) and Adak (2012, Alaska)

For additional information see the article"Review of the accomplishments of Mid-latitude Super Dual Auroral Radar Network (SuperDARN) HF Radars" in the journal Progress in Earth and Planetary Science (PEPS) at link)

This paper includes a 4-page supplementary file
titled "Historical Overview of Mid-latitude SuperDARN" available at the link link)

A news article describing the drafting of these papers via a pair of workshops hosted by Dr. Nozomu Nishitani (ISEE/ Nagoya University) can be found at: link)