The Northampton Pegging Machine Company, a manufacturer of various tools, began producing Langdon mitre boxes in Northampton, MA in 1864. Various improvements to the design of the miter box were incorporated in the following years, and by 1874 the general characteristics of the cast iron miter box as we know it today took shape.
Mitre boxes of the 1874-75 vintage have the words “Langdon Mitre Box”, “Northampton, Mass.”, “Pat’d Nov. 15, 1864″ cast into the backstop. The photos and measurements below are of two such examples. These particular specimens measure 19″ long, by 4” deep.
And here’s another one of similar age.
A Langdon Mitre Box Reference 