Sanford Health, with headquarters in Sioux Falls, S.D., is the nation’s largest nonprofit rural health care system, with 2012 revenues of $3 billion.

It operates 35 hospitals and 140 clinics in eight states, but is concentrated in the Dakotas and western Minnesota.

Previously known as Sioux Valley Health Care System, it changed its name to Sanford Health in 2007 after St. Paul native T. Denny Sanford made a $400 million donation. Sanford, who became a billionaire in banking and credit cards, has made additional gifts, bringing the total to more than $600 million.

Sanford Health merged with Fargo-based MeritCare in 2009, doubling its size and signaling an appetite for aggressive expansion. It created a third rural hub in Bemidji in 2011 by acquiring North Country Health Services.

Fairview Health Services, a $3 billion nonprofit, traces its roots to 1905, when several leading Norwegian citizens formed the Norwegian Hospital Association, with ties to the Lutheran Church.

Fairview is the second-largest health system in the Twin Cities, behind Allina Health, with about a 19 percent market share in the 13-county metro area, according to Standard & Poor’s.

Minneapolis-based Fairview operates eight hospitals, including the University of Minnesota Medical Center and University of Minnesota Amplatz Children’s Hospital. Fairview also runs 42 primary-care clinics in Minnesota and Wisconsin.

Fairview and the University of Minnesota have been partners since 1997, when Fairview bought the school’s financially distressed hospital. The deal came with a 99-year affiliation between Fairview and the university’s doctors.