Chinese cooking techniques to local produce and tastes has led to the development of American Chinese cuisine. Many of the Chinese restaurant menus in the US are printed in Chinatown, Manhattan, which has a strong Chinese-American demographic. In 2011, the Smithsonian National Museum of American History displayed some of the historical background and cultural artifacts of American Chinese cuisine in its exhibit entitled, Sweet & Sour: A Look at the History of Chinese Food in the United States. Differences from other regional cuisines in China American Chinese food builds from styles and food habits brought from the southern province of Guangdong, often from the Toisan district of Toisan, the origin of most Chinese immigration before the closure of immigration from China in 1924. These Chinese families developed new styles and used readily available ingredients, especially in California. The type of Chinese-American cooking served in restaurants was different from the foods eaten in Chinese-American homes. Of the various regional cuisines in China, Cantonese cuisine has been the most influential in the development of American Chinese food. One major difference between Chinese and American-Chinese cuisine is in the use of vegetables. Salads containing raw or uncooked ingredients are rare in traditional Chinese cuisine. However, an increasing number of American Chinese restaurants, including some upscale establishments, have started to offer these items in response to customer demand. While cuisine in China makes frequent use of Asian leaf vegetables like bok choy and gai-lan, American Chinese cuisine makes use of some ingredients not native to and very rarely used in China, for example, Western broccoli () instead of Chinese broccoli (gai-lan, ). (Occasionally, Western broccoli is also referred to as in Cantonese () in order to distinguish the two.) Chinese ingredients considered "exotic" in North America have become more available over time, including fresh fruits and vegetables which previously had been hard to find. For example, edible snow pea pods have become widely available, while the less-known dau miu (also called "pea sprouts", "pea pod stems", or "pea shoots") are also appearing on menus, and even in supermarkets in North America. American-Chinese food also has had a reputation for high levels of MSG to enhance flavor; however, in recent years, market forces and customer demand have encouraged many restaurants to offer "MSG Free" or "No MSG" menus, or to omit this ingredient on request. Egg fried rice in American Chinese cuisine is also prepared