COLUMBIA, S.C. — South Carolina’s two largest hospital systems are joining, as Palmetto Health in Columbia and Greenville Health System announced they’re creating a new organization Jan. 1.

The hospitals did not immediately say what the new system will be called, but it will have 13 hospitals and 28,000 employees, including 2,800 doctors. They will have more than 3,000 beds. The new group will be the largest private employer in South Carolina.

Hospital administrators say the system is expected to generate nearly $4 billion in annual revenue.

The nonprofit systems in Columbia and Greenville will operate separately, with a joint board. No money is being exchanged.

Palmetto Health chief executive Charles Beaman said the partnership is the result of nearly a year of work. He notes the two systems have worked together for a long time, and co-own Baptist Easley Hospital.

“We said, ‘Let’s take what we’re doing and see if we can do something better,'” Charles Beaman, chief executive officer for Palmetto Health, said.

There are no immediate plans for staff reductions, but Beaman said some consolidation is possible.

Officials say the approval was unanimous by both hospital boards. The boards will combine with equal representation from each. The companies’ chief executives, Beaman and Greenville’s Michael Riordan, will become co-CEOs and share leadership responsibilities.

The University of South Carolina opened a medical school next to Greenville Memorial Hospital in 2012. USC is also moving its Columbia medical school campus to a site near Palmetto Health Richland. USC and Palmetto Health merged medical practices last year.

Patrick Cawley, CEO of the Medical University of South Carolina in Charleston, said he’s not surprised by the merger, pointing out one way the health care industry tries to reduce costs is to consolidate.

Beaman said the merger is designed partially to help cope with uncertainty in the health care market, as Congress tries to replace the Affordable Care Act.

“There are a lot of unknowns facing the health industry starting with how we’re going to be reimbursed in the future,” Beaman said.

Those concerns were echoed by Greenville’s Riordan.

“We’re not seeing more money on the horizon,” he said, pointing to proposed Medicaid cuts.