From the New Yorker:
In the late nineteen-twenties, two companies—Kellogg and Post—dominated the market for packaged cereal. It was still a relatively new market: ready-to-eat cereal had been around for decades, but Americans didn’t see it as a real alternative to oatmeal or cream of wheat until the twenties. So, when the Depression hit, no one knew what would happen to consumer demand. Post did the predictable thing: it reined in expenses and cut back on advertising. But Kellogg doubled its ad budget, moved aggressively into radio advertising, and heavily pushed its new cereal, Rice Krispies. (Snap, Crackle, and Pop first appeared in the thirties.) By 1933, even as the economy cratered, Kellogg’s profits had risen almost thirty per cent and it had become what it remains today: the industry’s dominant player.