This practice remained until the late 1970’s, when bureau precancels stopped having city names printed on them. Local precancels still do have city names between two lines. Users had to obtain a permit, so that the post office could keep a lid on re-use of precancels. It was against regulations for the permit-holder to sell mint precancels to anyone else.
Precancels had their hey-day in the 1920’s, when they were used on virtually all bulk mail and much parcel post. Since then they’ve been in gradual decline until today, when there are probably only 5-10 post offices in the country still using precancels with city names, other than philatelic usage. This decline was due partly to the postage meter, which gradually replaced stamps on parcel post, and partly to bulk-rate printed indicia’s which replaced stamps on bulk mail. Thus it wasn’t that the idea of precancelling became outdated, it was that the use of postage stamps became less efficient than other methods of paying the postage.
A ver si hay suerte.
Saludos.