In his book New York Food (Stewart, Tabori & Chang, 2004), Arthur Schwartz explains that many Jews at the time "lived in tenements with minimal cooking facilities. An already 'cooked' product like lox was akin to convenience food". Not only was it inexpensive, but, like all fish, it was pareve, meaning that, unlike meat, it could be eaten with dairy. Lox thus became a staple of "appetizing" stores that specialized in dairy and cured fish. By the 1930s, many smokehouses had opened in New York to preserve the fresh Pacific salmon arriving by refrigerated rail. Variations on lox emerged, the most popular being nova scotia—nova, or sometimes novy, for short—which differed from lox in that it was smoked and made with Atlantic salmon that came from fisheries in and around the Canadian province of Nova Scotia. As trade expanded over the course of the 20th century, big-city smokehouses in America also began replicating versions arriving from places with their own smoked-salmon traditions, like Ireland, Scotland, and Denmark.