Commercial mayonnaise sold in jars originated in New York City, in Manhattan's Upper West Side. In 1905, the first ready-made mayonnaise was sold at Richard Hellmann's delicatessen on Columbus Avenue, between 83rd and 84th Streets. In 1912, Mrs. Hellmann's mayonnaise was mass marketed and called Hellmann's Blue Ribbon Mayonnaise.
At about the same time that Hellmann's Mayonnaise was thriving on the East Coast of the United States, a California company, Best Foods, introduced their own mayonnaise, which turned out to be very popular in the western United States. Head-to-head competition between the two brands was averted when, in 1932, Best Foods bought out the Hellmann's brand. By then both mayonnaises had such commanding market shares in their own half of the country that it was decided that both brands and recipes be preserved. To this day, Best Foods Mayonnaise is only sold west of the Rocky Mountains, while Hellmann's is sold east of the Rockies.