Sushi has taken on its own shape and form in the United States, but even before the first sushi restaurants opened up in California, America had an impact on the type of sushi eaten in Japan. During the American occupation after World War II, a food rationing program helped the rise of nigiri outside Tokyo.
Original salmon nigiri photo by jh_tan84 (CC BY 2.0).
When many Americans think of sushi, chances are that they think of makizushi, the (usually) seaweed-wrapped rolls cut into slices, or nigirizushi, the rectangles of rice often topped with a single piece of fish or slice of omelette. Nigiri is, however, a relative newcomer to Japanese cuisine, invented some time during the 19th century. A sushi shop owner named Yohei Hanaya is often credited with created the hand-squeezed nigiri, but he may have just been the most successful early vendor of the dish. But nigiri definitely got its start in Edo, the city which was renamed Tokyo just a few decades later.
While nigiri quickly became the most popular style of sushi in Edo, it did not immediately dominate the sushi landscape as it does today. In his book The Story of Sushi, Trevor Corson credits two events with the rise in popularity of nigiri outside of Tokyo: One is the Great Kanto Earthquake of 1923, which forced many people (including sushi chefs) to leave Tokyo for their hometowns. When the Tokyo sushi chefs opened up sushi restaurants back home, they made Edomae (Edo-style) sushi, with an emphasis on nigiri. The other event is where the Americans come in.
Following World War II, American forces, led by General Douglas MacArthur, occupied Japan. Now, it wasn't Americans eating sushi that had an impact on sushi-making during the occupation; it was rather how the Americans oversaw food rationing. Many sushi shops had been forced to close during the war due to rice-rationing, and even after the war, shops were not able to obtain enough rice to reopen. In The Sushi Experience, chef and Japanese culinary expert Hiroko Shimbo credits Kataro Kurata, who was a chef at the restaurant Sushi-ei in Tokyo's Ginza district, with appealing to the staffers at the American forces' general headquarters, impressing upon them the importance of sushi to Japanese culture. Eventually, the shops were allowed to be opened, but under one condition: that the shops use the rice brought to them by customers. If someone wanted sushi, they would have to bring their own rice rations to the shop, where a chef would use that rice to make sushi for the customer.
This "consignment" process came with some very rigid strictures: one cup of rice was to make ten pieces of sushi, seven nigiri and three piece of thin roll. After it proved a success in Tokyo, Corson says, the same system was implemented in other parts of the country, with the same requirements: that a certain amount of rice produces certain amounts of specific sushi types. These regions had their own types of sushi, and while these regional varieties of sushi have by no means died out, Tokyo-style nigiri became Japan's predominant form of sushi.
Shimbo points to one other side effect of this rice rationing program: nigiri shrank in size. Before one cup of rice was expected to make ten pieces of sushi, a single piece of nigiri was three times larger in prewar Japan. But in some US restaurants, the size of nigiri is growing again, reversing the process that the Americans oversaw during their occupation.