The address is actually 54-64 Hanover Street NW, which is a warehouse. And I will say was a warehouse in 1923 when the below correspondence was written.
Not sure what the deal was as I only have the two letters. Both letters are from H. Jeffrey. It looks like he changed his business name, or at least used different letterhead in February and May of 1923 when writing to the Rent Commission of the District of Columbia. In February it was H. Jeffrey And Company, an import, government surplus, chemical, drugs and oils business. In May he was apparently running a paper box company with the Columbia Specialty Paper Box Company.