Thanks for the information and clarification that the precancel is from "Station H". Apparently, in its day, "Station H" commanded quite a workforce, as noted in this excerpt taken from a book dated back to 1908:
NEW YORK.
Grand Central Station Rays.This station, Its new name, "Grand Central," formerly named Station H, is the largest branch station in the United States, its distribution and city delivery departments employ over 500 clerks or one-sixth of the entire New York force, or one sixty-second of the entire number of clerks in the Post Office Department. We employ as many clerks as the Baltimore office and more than any other entire city office excepting Chicago, Boston, Philadelphia and St. Louis. We handle more mail matter of the various classes than any entire city office excepting four cities, Chicago, Boston, Philadelphia and St. Louis. We handled more second-class matter in 1908 than any other entire city office excepting Chicago, which is a close rival. We of this great big station, almost a large city force by ourselves, are a vital force in the wonderful machinery of the postal service, and are intensely interested in all that pertains to advancing the interests of the service and of the rank and file.
THE UNION POSTAL CLERK, 1908