Carlyle Group, a District-based private equity firm, has reached an agreement to acquire nursing home operator Manor Care for $6.3 billion, the companies said in a statement on July 2.

Manor Care runs more than 500 nursing homes and assisted living centers across the United States and employs more than 60,000 people. The company, which was founded in 1959 by Stewart Bainum Sr., has deep roots in the Washington region and for years was based in Montgomery County.

In 1998, Manor Care merged with rival Health Care and Retirement Corp. in a $2.9 billion stock swap, and moved its headquarters to Toledo, Ohio.

Stewart Bainum Jr., the founder’s son, stepped down as chairman in 2002. He is chairman of Choice Hotels International, a Silver Spring hospitality firm that was a unit of Manor Care before being spun off as a separate company in 1996.