Plum Creek Timber Co. and Weyerhaeuser announced Sunday the two companies would merge, creating the largest private owner of timberlands in the U.S. with more than 13 million acres in timber and other land holdings. Under the terms of the agreement, which has been unanimously approved by the boards of directors of both companies, Plum Creek shareholders will receive 1.6 shares of Weyerhaeuser for each share of Plum Creek held. The transaction is contingent on shareholder approval. The merged company will be called Weyerhaeuser. Combined, the two companies will have a equity value of $23 billion based on current share prices. Plum Creek owns 6 million acres of timberlands in 19 states. Weyerhaeuser owns or controls nearly 7 million acres of timberlands, primarily in the U.S., and manages additional timberlands under long-term licenses in Canada.

Locally, Plum Creek employs about 750 workers in its Flathead Valley mills — the bulk in Columbia Falls, with an annual payroll of about $60 million. Weyerhaeuser has about 12,800 employees worldwide and had $7.4 billion in sales in 2014. Plum Creek CEO Rick Holley will remain with the company as non-executive chairman of Weyerhaeuser’s board, while Doyle R. Simons, currently the president and chief executive officer of Weyerhaeuser, will remain CEO of the combined company. The merger is expected to close in late first quarter or early second quarter of 2016.