The Cement Belt: Where Portland Cement Was Born in America

The limestone underneath the Lehigh Valley is the reason much of modern America is paved the way it is. This ground, this particular chemistry of calcium carbonate and clay minerals, was one of the critical geological accidents that made the United States a concrete civilization.

Portland cement requires limestone in a fairly specific mineral composition, and the Lehigh Valley had it in extraordinary abundance. The first American Portland cement was made in a small plant along the Lehigh Canal in eighteen seventy-five. Within two decades, the valley had become the production center for the entire American cement industry, a fact so important that engineers and manufacturers used a specific phrase for the concentration of plants that stretched from Allentown east toward Easton: the Cement Belt.

Lehigh Portland Cement Company was founded in eighteen ninety-seven by six Allentown businessmen who invested two hundred and fifty thousand dollars to build a plant in nearby Ormrod. By nineteen twenty, it was the largest cement company in the country by number of plants, with an annual output of more than twelve million barrels. Twelve million barrels of cement per year from one company, in one valley, in one state.

The scale of what was built with Lehigh Valley cement is almost impossible to overstate. The Panama Canal. Highways. Bridges. The skyscrapers rising in New York and Chicago and Philadelphia in the early twentieth century used cement that almost certainly passed through this valley on its way to a construction site.

The Cement Belt eventually declined as limestone was exhausted and competitors developed elsewhere. Lehigh Portland Cement was sold to a German company, Heidelberger Zement, in nineteen seventy-seven. Today HeidelbergMaterials, as it is now named, remains one of the world's largest building materials companies, still tracing its American roots to six businessmen in Allentown with a limestone hill and a vision.