In the March 18, 1989, issue of Billboard magazine, Geoff Mayfield (our then-senior editor, retailing), reported:
"Russ Bach, the newly appointed president of CEMA [an acronym for the company that once distributed Capitol Records, EMI Records, Manhattan Records and Angel Records] made a call for the industry to adopt Tuesday as the universal street date for new releases; by the end of the meet, he almost had his wish. PolyGram, like CEMA, announced it would move its street date to Tuesday, which leaves MCA as the sole vendor with Monday debuts. Bach's concern is that many stores received key product too late in the day [Monday] under the old system."
Billboard offered up this update the following week (March 25):
"Beginning in April, [PolyGram] will make Tuesday its street date. With CEMA making a similar announcement at NARM, all of the majors except MCA will now have a Tuesday street date." (MCA would later move to Tuesday as well.)
We reached out to Mayfield -- who later served as Billboard's director of charts from 1994 to 2008 -- for further explanation on the shift from Monday to Tuesday. He echoed Bach, saying some stores wouldn't get their delivery of new product until late on Monday, many hours (or days) after competing stores would get the same exact product (and would have likely started selling it).
Also remember: This was in the pre-digital era, where essentially the only way to obtain music was to go to a store and buy an album or a single.
So the industry moved the universal release date to Tuesday in order to level the playing field, better ensuring that everyone would have that week's new releases ready to sell at the same time.