This question has boggled my mind for decades (2 to be exact)! So for no reason at all, I decided to google it and now I know. Here you can find more random trivia about Heinz. Check out their ads too!
What does the “57” stand for in Heinz’s famous slogan, “57 Varieties?”
While riding a train in New York City in 1896, Henry Heinz saw a sign advertising 21 styles of shoes, which he thought was clever. Although Heinz was manufacturing more than 60 products at the time, Henry thought 57 was a lucky number. So, he began using the slogan “57 Varieties” in all his advertising. Today the company has more than 5,700 products around the globe, but still uses the magic number of “57.”