MI: Map of Michigan HRRs Michigan Hospital Referral Regions The above map shows the Hospital Referral Regions in the state of Michigan. It was obtained from a publication of the Center for Healthcare Research & Transformation (CHRT; link: chrt.org). The map can be found as a part of a report at http://www.chrt.org/publication/health-care-variation-michigan-chrtbook/. Copyright © 2008–2014 Center for Healthcare Research & Transformation.