Securities exchanges shutdowns

[GMUresearch]

Armchairs, I was told that in the late 1960s, early 1970s, there were occasions when securities exchanges shut down because they were unable to keep up with all the paper they were generating (especially with clearing and settlement). This backlog may have forced exchanges to innovate their back offices, or to embrace new technologies and so on...    Does any of you know if this shutdowns were true or where can I find some related information?  I wonder if similar shutdowns have occurred in more recent times.  I am digging for some citations and dates here but I am not old enough to remember! -JA