WARRENVILLE, Ill. — National Express Group has completed its acquisition of Petermann, company officials announced on Monday.

Cincinnati-based Petermann will join National Express' U.S. school bus contracting brand, Durham School Services.

National Express announced in September that it had signed an agreement to acquire Petermann. Both companies are among the 10 largest school bus contractors in the U.S. and Canada.

The U.S. Department of Justice announced on April 30 that National Express and Petermann would divest several school bus contracts to resolve antitrust concerns and proceed with their merger.

The deal reportedly closed the next day.

Company officials said that the acquisition strengthens National Express' position in the student transportation market, increasing its fleet size to more than 20,000 school buses across North America. (National Express also operates Stock Transportation in Canada.)

"We are thrilled to add this solid brand to our U.S. operations, and are excited to welcome Petermann customers and employees to our family," said David Duke, CEO of National Express Corp. "Our customers and employees will continue to see operational excellence with an intense commitment to safety and outstanding service."

The combined company now serves more than 400 school districts in 32 states and four provinces, official said.

Petermann CEO Pete Settle called National Express "the perfect home for Petermann. Petermann employees share Durham's focus on their values of safety, people, customer and community; we are proud to be part of the National Express family."

Settle founded Petermann LLC in early 1999, and the business soon began growing rapidly. In 2002, SCHOOL BUS FLEETnamed Settle its Contractor of the Year.