Many pre-1900 book titles are subtitled by giving an alternate title using "or" (e.g. 'Frankenstein; or, the Modern Prometheus'). When and why did this fall out of use?

by chivestheconquerer

"Pre-1900" is not to imply that that is when the change took place, it's just my personal observation that the trend of giving an alternate title using "or" was more common in 19th-century texts.

I understand that we do subtitle movies and books today using text after a colon, but when and why did this come to prominence?

GeeJo

You may find this comment on the topic, written by /u/bloodswan last year, to have some useful material. It covers the trend of English works with both the lengthy subtitles you mention, and the smaller ": a Novel" subtitle fashion.