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Glenn L. Martin Aircraft Company Plant No. 2

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Middle River Depot
1941, Albert Kahn Associates. 2800 Eastern Blvd.
  • Glenn L. Plant Co. Plant No. 2, Assembly (rear) and Drop Hammer (Photograph by James Rosenthal, HABS)
  • Assembly building (Photograph by James Rosenthal, HABS)
  • Telescoping doors at high bay of Assembly Building (Photograph by James Rosenthal, HABS)
  • Interior, Assembly Building (Photograph by James Rosenthal, HABS)
  • Interior, Assembly Building (Photograph by James Rosenthal, HABS)

The Baltimore County community of Middle River was a vital manufacturing center during World War II due to the expansion of the pioneering Glenn L. Martin Aircraft Company. Martin worked repeatedly with the innovative Detroit architectural and engineering firm of Albert Kahn Associates. His Plant No. 1 in Middle River was started in 1928, but it was a series of expansions built in anticipation of World War II, including Plant No. 2, that emerged as landmarks in modern industrial engineering.

In 1937 Kahn designed a new Assembly Building for Plant No. 1. Using parallel-chord roof trusses adapted from bridge technology, the Assembly Building offered an unobstructed 300 x 450–foot interior for manufacturing aircraft at an unprecedented scale; another Kahn addition was added to Plant No. 1 in 1939. Plant No. 2 was built in 1941, approximately one mile from the first plant. Completed in November, Plant No. 2 repeated the successful design elements of Kahn’s previous work for Martin Aircraft, including a 602 x 900–foot Assembly Building with parallel-chord bridge trusses. It was the first factory expansion funded by the federal government under the Emergency Plant Facilities Act. As such, the Army Air Corps leased the factory to the Martin Company for production of B-26 Marauders.

Plant No. 2 encloses over one million square feet of space. Kahn took advantage of the site’s natural grade to provide a basement level, an unusual feature for an aircraft factory. Supported by ten concrete mushroom columns and open on three sides, the basement housed manufacturing processes such as creating parts and sub-assembly. The assembly areas on the first floor have steel columns spaced 50 x 100 feet with a truss clearance of 22 feet. The 28-foot-tall “high bay” at the west end of the Assembly Building, with its 100 x 200–foot span, accommodated final aircraft assembly. Massive telescoping cantilevered doors allowed the assembled B-26 Marauders to be moved to the Paint Shop and then the adjacent Pennsylvania Railroad for delivery. The complex also included an administration building, oil house, boiler house, and drop hammer building.

Between 1939 and 1943, the number of Glenn L. Martin employees in Middle River surged from 3,000 to 52,000. Many nearby residential neighborhoods, including Victory Villa, Aero Acres, and Stansbury Estates, were built as defense worker housing in response to the expansion by Martin Company. Lockheed Martin continued manufacturing at a much altered Plant No. 1 until 2010. Plant No. 2 survived remarkably intact, having been used for many years as a warehouse by the U.S. General Services Administration (GSA). In 2006 the property was sold to private developers and remains slated for mixed-use redevelopment that would retain the historic buildings.


Breihan, Jack. “Necessary Vision: Community Planning in Wartime.” Maryland Humanities 71 (November 1998): 11-14.

Hildebrand, Grant. Designing for Industry: The Architecture of Albert Kahn. Cambridge: MIT Press, 1974.

Writing Credits

Lisa P. Davidson
Lisa P. Davidson
Catherine C. Lavoie



  • 1941


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Lisa P. Davidson, "Glenn L. Martin Aircraft Company Plant No. 2", [Middle River, Maryland], SAH Archipedia, eds. Gabrielle Esperdy and Karen Kingsley, Charlottesville: UVaP, 2012—,

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