![[Beyond Steel Logo]](http://digital.lib.lehigh.edu/beyondsteel/skyline.gif)
However, it is important to stress that the adoption of the rotary kiln was not the sole reason for the explosion of the American cement industry. Demand for cement was also increasing internationally. In the 1880s the commercially successful passenger elevators were developed, enabling the construction of skyscrapers with skeleton frames of concrete walls around steel or iron frames. Stronger Portland cement, initially in Germany, made reinforced concrete construction practical and by the 1890s the range of uses for reinforced concrete had expanded considerably and therefore the demand for cement. As cities grew so did the demand for fire control, which concrete buildings assisted with. Though these demand factors are important, the fall in the real price suggests the cost-reducing effects of the rotary kiln were greater than the demand increasing effects on price. The increase in quantity is determined by both the increase in demand and supply.
The Lehigh Valley had three advantages that contributed to its playing a central role. First it is relatively near three major centers of population: New York and New England, Philadelphia and Washington DC. Second, it is relatively near Lima OH, the main source for fuel oil required for the rotary kiln. The third, possibly critical, advantage is that the raw materials of the Lehigh Valley are relatively simple to work with as they closely match the chemical composition required for Portland cement and are free of impurities that prevented, for example, large-scale production of Portland cement in the Rosendale area.
Some other manufacturers within the Lehigh Valley and at other locations where oil was cheap, such as in Ohio and Southern California, also adopted the rotary kiln. But, with the rise of Rockerfeller's Standard Oil, the price of oil rose and was expected to rise further. The third event that enabled the rotary kiln to diffuse across the United States was the adaptation, by the engineers Hurry and Seaman at the Atlas Portland Cement Co., of the rotary kiln to burn with cheap pulverized coal instead of a fuel controlled by a monopolist. The patent for this invention became known as the Hurry-Seaman patent. Now the rotary kiln could be used outside of southern California and the central northeastern states, and the industry diffused rapidly throughout the U.S. and internationally.
The most rapid expansion occurred in the Lehigh Valley with a set of plants forming what became known as the cement belt. The belt began in the west at the Ormrod plant of the Lehigh Portland Cement Co. To the east of Ormrod was the set of plants in Whitehall Township, Lehigh County, including Coplay. To the east of these plants was the set of plants around Northampton, Northampton County, just across the Lehigh River from Whitehall, including the large new plant of the Atlas Portland Cement Co. The next set of plants was again across to the east around Upper Nazareth Township. The eastern end of the belt then frays around Easton. North-east of Easton, on the west bank of the Delaware River, still in Northampton County, there were to be three plants. Across the river from Easton were the three sets of plants in Warren County, New Jersey. The easternmost plant was that of the (Thomas) Edison Portland Cement Company, near Stewartsville. Thomas Edison made his own contribution to the cement industry during this period in developing much larger kilns which, again, quickly diffused beyond the Lehigh Valley.
