A full-page article in Music Trade Review (MTR) of October 2, 1920,
page 16, announces the new QRS music roll production plant in The
Bronx, New York:

  "The new modern plant of the Q R S Music Co., located at 135th street
  and Locust avenue, New York, is now operating under practically full
  capacity.  It is under the personal management of Lee S. Roberts,
  vice-president of the Q R S Music Co., whose experience in the
  manufacturing of music rolls has been of long duration and whose
  authority on proper merchandising is generally acknowledged."

Two statements in the article hint at the magnitude of the piano roll
business in 1920:

(1) "On these floors twenty or more of the most modern double
perforating machines have been installed."

(2) "... its capacity output, which is thirty-five thousand rolls
per day."

Whew!  That's the capacity to produce about 9 million rolls per year!

Thanks to the MBSI and Arcade Museum for making the Music Trade Review
and Presto magazines available for on-line research, and thanks to
Bob Billings and John McClelland for the tip to the MTR article at

https://mtr.arcade-museum.com/MTR-1920-71-14/16/ 

Robbie Rhodes