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 https://doi.org/10.1186/s40645-019-0270-5(external link)

This paper includes a 4-page supplementary file
titled "Historical Overview of Mid-latitude SuperDARN" available at the link
https://static-content.springer.com/esm/art%3A10.1186%2Fs40645-019-0270-5/MediaObjects/40645_2019_270_MOESM1_ESM.pdf(external 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:

http://vt.superdarn.org/tiki-read_article.php?articleId=317(external link)