When and why did conferences pick up the habit of giving out conference bags to attendees? I wonder when and why conferences picked up the habit of giving out conference bags to attendees.
For the why part: One reason is to make registration at the conference as smooth as possible. Imagine the first morning of a conference and all the attendees at the registration desk lining up and for each and every participant the guy at the desk hands over the program, the book of abstracts, the badge, the ticket for the conference dinner, the ticket for the prebooked tour (if there is any), the receipt of attendance, the receipt of payment, the complimentary notebook and pen and, of course, the stuff from sponsors. Takes much longer than pre-packed bags. (And even with all things pre-packed, there are always queues during the rush hour.

As for the when part, I have no idea. But if you have ever sat at  a conference desk you'll agree that it must have been no later than the first time one guy organized a conference with more than 100 people for the second time.