By the 1930s, the building housed 500 employees who produced millions of mail sacks and hundreds of thousands of locks each year, designed and patented various pieces of equipment. and annually cleaned and repaired as many as five million mail sacks. The equipment shop was the only major location for mail equipment repairs through 1954. and remained the sole manufacturer of mailbags. locks. individual mail boxes, and keys until 2002. These seemingly mundane functions enabled the delivery of the nation's mail for nearly a century. The building is also one of the first large reinforced-concrete column-and-slab buildings in Washington, brought about by the federal government's early interest in such fireproof facilities.
The MES building retains sufficient integrity to convey its significance as the sole mail
equipment shop of the Post Office Department and as an early example of a fireproof reinforced concrete warehouse in Washington, D.C. Within its setting the MES also retains sufficient integrity to convey its significance at the local level as an example of the early twentieth-century construction of industrial buildings along the Metropolitan Branch of the B&O Railroad. Although aspects of the building have been altered, the majority of these changes were made within the established period of significance and illustrate the upgrading of the building as technology and the needs of the MES changed.
Nominated by the property owner and designated May 26, 2016
National Register: July 11, 2016