Lock Ridge Furnace
Written by Martha Capwell Fox, DLNHC Historian
The cast house and base of the blast furnace at Lock Ridge Furnace Park in Alburtis were the heart of the iron works when it was operating. Today, they are the only intact surviving structures of the many anthracite iron furnaces that made the Lehigh Valley the center of iron production in the middle of the 19th century.
Lock Ridge Furnace was built in 1868 by the Thomas Iron Company, which also had iron works in Hokendauqua and Hellertown. Like the other iron furnaces in the Lehigh Valley, it produced pig iron smelted from a mix of local limonite iron ores and magnetite iron ore from both nearby Rittenhouse Gap and the Thomas mines in Morris County, New Jersey. And while other furnaces eventually changed their main fuel to coke (soft coal that is “baked” to increase its energy content), Lock Ridge Furnace was still using anthracite in 1915, though it had switched to smelting a higher percentage of New Jersey magnetite.
An article published in the Allentown Morning Call on July 6, 1915 reported that the two furnaces, the only original ones still in blast in the Lehigh Valley, were producing record amounts of high-quality iron, turning out just over 3800 tons in May 1915. By that time, only the Thomas Iron Company and the Empire Steel and Iron Company (the former Crane Iron Works) in Catasauqua were producing pig iron. World War I offered a brief reprieve to the industry, but the post-war combination of a deep economic recession and the influenza pandemic drove both companies out of business in the 1920s.
As it was one of the later furnaces to be built, Lock Ridge relied on railroads rather than the Lehigh Canal to deliver raw materials and haul away the pig iron. The former tracks have been converted to trails that let visitors explore the site. Lehigh County Historical Society offers open-air tours from May through September and there are many interpretive panels.
An extensive description of the operations of Lock Ridge Furnace can be found in The Anthracite Iron Industry of the Lehigh Valley by Craig Bartholomew and Lance Metz. It is out of print but can be found on some online used book sites.
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