The only grouping of Frank Lloyd Wright's early American System-Built Homes—built by Arthur Richards and designed with standardized components for mass appeal to moderate-income families—is situated in the Burnham Park neighborhood in Milwaukee, Wisconsin. The four model 7A duplexes, one model B1 bungalow (shown here), and model C3 bungalow were added to the National Register of Historic Places in 1985. [Photo via McNees.org]
Another house built from Wright's Prefab #1 plan for Marshall Erdman & Associates, the Socrates Zaferiou House in New York state, was sold in 2014. 

The Prefab #1 layouts, which ranged in size from 1,800 to 2,400 square feet, shared a single story, L-shaped plan with a "pitched-roof bedroom wing joining a flat-roofed living-dining-kitchen area centered on a large masonry fireplace." Alongside prefabrication managed by Erdman's company, the architect sourced off-the-rack Andersen windows and Pella doors and used basic materials like plywood and Masonite to cut costs. [Photos via Curbed]
New York City boasts only two Frank Lloyd Wright structures: the Guggenheim Museum, and this modest prefab on Staten Island. The Cass House was built according to the Prefab #1 plan he designed for Erdman's prefab company. According to the New York Times, "It was built late in his life from a plan for prefab moderate-cost housing. The components were made in a Midwest factory and shipped to Staten Island for construction under the supervision of a Wright associate, Morton H. Delson... Wright had planned to tour the Staten Island house, but shortly before his scheduled arrival he became ill and died at age 92 on April 9, 1959." [Photo via Bridge and Tunnel Club]
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