Adams Publishing Group, the Coon Rapids-based owner of community newspapers, is boosting the size of its holdings by about 10% with the acquisition of Yellowstone Newspapers, the largest newspaper group in Montana.

The deal, announced Monday, will add 13 newspapers to Adams Publishing's portfolio of 120 newspapers and 220 related digital outlets in 19 states across the country. Terms were not disclosed.

Adams Publishing already owns the Daily Chronicle and several other publications in Bozeman and nearby Belgrade.

"This opportunity is a great strategic fit with our Big Sky region based in Bozeman, and we look forward to providing that region with greater regional and local community journalism as well as a larger advertiser audience," Mark Adams, chief executive of Adams Publishing, said in a statement.

Yellowstone Group started in 1965 with the purchase of the Miles City Star. Its holdings include the Livingston Enterprise, a daily in Livingston, about 25 miles east of Bozeman. The company also owns newspapers in Lewistown, Big Timber, Dillon and several other towns.

The 13 news organizations employ about 100 people.

For Adams, the deal will make Montana the anchor of its holdings in the Pacific Northwest. It owns a smaller number of publications in Idaho, Oregon, Washington and Wyoming.

The company has a sizable presence in the Southeast and mid-Atlantic regions. It owns more than 60 print and digital publications in Minnesota and 22 in Wisconsin.