President Warren Harding died in office after a short illness. He is generally considered as one of the worst US Presidents. In normal circumstances, his death would not be commemorated on a stamp, indeed not so soon after his demise. After all, the last such mourning stamp was the 1866 Lincoln 15¢ issued some years after his death. The Lincoln mourning stamp was also printed in black. But Mr. New, the Postmaster General at the time, was a friend of the late Warren Harding, and he wanted a mourning stamp for him.

#613 was created when a sheet of the rotary press stamps was fed through the flat plate (Gauge 11) perforator

The portrait used was Harding's favorite, taken just before his death. The stamp proved to be very popular. So much so that the print run was doubled and the time on sale extended. Still, the Bureau could not keep up with demand. The flat plate presses worked to the max, and shortages occurred. So for the first time, a commemorative stamp was printed in both flat plate and rotary press as the latter was employed to assist in production.

An imperforate stamp was also sold. The reason was not for postage; it was for folks who wanted to display sheets of 100 stamps in a frame to celebrate Harding.

A die proof of Warren Harding