"W.E. Long, who promoted the Holsum Bread brand, used
by various independent bakers around the country, pioneered and
promoted the packaging of sliced bread beginning in 1928. In 1930
Wonder Bread, first sold in 1925, started marketing sliced bread
nationwide." [source: Wikipedia]
So, sliced bread comes AFTER the automobile, the airplane and the radio, and only a few years before jet airplanes, rockets, the atom bomb, and the first computers.