James Lileks pointed me to this.
On July 6, 1928, in the small US town of Chillicothe, Missouri, the local newspaper broke the story on the front - and carried the advertisement on the back - of its eight page edition. From the following morning the Chillicothe Baking Company would be selling pre-sliced bread at quality grocers in the area, thanks to a powerful multi-bladed machine called the Rohwedder Bread Slicer.
It had been some time coming.
The bread slicer that made it all possible was invented by Iowa man Otto Rohwedder who built his first prototype in 1917 but it was not put into commercial use until 1928 when the Chillicothe Baking Co. took it on.
Thus was the standard for future inventions set. The significance has dimmed with time, but anyone who has attempted to slice bread manually understands why this was a big deal.