It’s like asking where bread comes from. Or more to the point: pie. The small pie — the “pocket pie” — just seems to be one of those good ideas that a lot of different people all came up with, more or less all at the same time. The Cornish had their pasties, the Spanish their empanadas, the Russians their pirozhki, the Portuguese their rissoles, the Scottish their bridies, the Italians their calzones, and the Eastern Europeans — especially the Eastern European Jews — their knishes. It was this group, it’s thought, that first brought the knish to American shores, if by “shores” you mean the Lower east Side of Manhattan. It’s there that the knish really caught fire, as it were, around the turn of the (last) century. The reasons why are easy enough to guess. They were cheap, hot and filling. And for bakers, they were an easy thing to make in great, great quantity.
One of the first people to get famous making knishes for the masses was a Romanian Rabbi by the name of Yonah Schimmel. He is credited with being the first entrepreneur to begin selling knishes on the street from a pushcart. In time he brought his operation to Coney Island, where, for reasons that are still not fully understood by scientists, he made a small fortune selling piping hot potato pies to sunbathers on 90-degree days. In 1910 he opened his now legendary knishery on Houston Street, and it stands there, still churning out Schimmel’s classic knishes, to this day.