The iconic cement plant at Monolith, east of Tehachapi, has officially changed hands.

Martin Marietta Materials, Inc., became the fifth owner of the plant since its construction by the city of Los Angeles 115 years ago.

Martin Marietta Materials is a leading supplier of construction aggregates and heavy building materials, with more than 500 locations spanning 30 states, Canada and the Caribbean.

In May, the company announced the acquisition of the plant and other assets of Lehigh Hanson, Inc.’s West Region business for $2.3 billion in cash. The sale required regulatory approval and was finalized on Oct. 1.

Lehigh Hanson, Inc., and its affiliated companies are part of HeidelbergCement Group, one of the largest building materials manufacturers in the world. Lehigh purchased the plant in 1995.

“We are pleased to complete the Lehigh West Region acquisition and welcome a talented group of new employees to the Martin Marietta team,” said Ward Nye, chairman, president and CEO of Martin Marietta, when completion of the acquisition was announced. “These assets serve as a new growth platform for our continued geographic expansion and are uniquely positioned to benefit from favorable market dynamics and accelerating public and private construction activity in California and Arizona.”

The acquisition provides the company with 17 active aggregates facilities, cement plants in Tehachapi and Redding and related distribution terminals, and targeted downstream operations serving key California and Arizona regions including the Bay Area, Los Angeles, San Diego and Phoenix.

According to the International Cement Review (online at, the new western markets have expanded Martin Marietta's cement operations so that it has coast-to-coast coverage. The publication cited current economic drivers for the company including an anticipated boost from the bipartisan Infrastructure Investment and Jobs Act.

The trade publication speculated that the west region sales would provide HeidelbergCement “with a substantial sum to help reinvest in the restructuring of its building material businesses in global markets.” HeidelbergCement’s previously announced strategy is to simplify its portfolio with a prioritization on the strongest-growing markets.

HeidelbergCement’s Permanente cement plant and quarry (in Cupertino) was not included in the deal. The plant has been idle since 2019 and regional press reports indicate Lehigh has been stymied in its expansion efforts there.

The Tehachapi plant, according to, is the most modern of the three cement plants. Both the Tehachapi and Redding plants were among four Lehigh Hanson plants that won the EPA’s Energy Star certification in 2018. 

“The California cement market is still proving to be the most productive of the U.S. states,” reported in May when the sale was announced, “...which is surely a pull factor for Martin Marietta. However, the environmental legislation in the state is amongst the toughest in the country and Lehigh Cement has had to invest U.S. $12m in environmental control technology in California as part of a settlement with the U.S. EPA for alleged violations of the Clean Air Act.” 

Headquartered in Raleigh, N.C., Martin Marietta Materials, Inc. is a member of the S&P 500 Index.

The company’s corporate heritage descends from an aggregates company, Superior Stone, founded in 1939 in Raleigh. That company was purchased by the American-Marietta Corporation, an industrial conglomerate, in 1959. A merger with the American aircraft and aerospace company, the Glenn L. Martin Company, in 1961, resulted in the Martin Marietta Corporation, which eventually merged with the aerospace company Lockheed to form the Lockheed Martin Corporation in 1995. In 1996 Martin Marietta Materials, Inc., was spun off as an independent company separate from the defense, aerospace and other lines of Lockheed Martin.

Claudia Elliott is a freelance journalist and former editor of the Tehachapi News. She lives in Tehachapi and can be reached by email: