New York's Chinatown began in the mid 19th century as Chinese immigrants who were facing legal and social discrimination on the West Coast moved to the East Coast in search of work, primarily in laundries and restaurants. Chinatown started around Mott Street east of the Five Points district. A population of 200 in 1870 grew to 2,000 in 1882 when the Chinese Exclusion Act was passed and began limiting legal Chinese immigration, especially of women. Although there were 7,000 Chinese living in Manhattan in 1900, only around 2% were women, creating an imbalanced "Bachelor Society".
The Exclusion Act was lifted in 1943, granting China a small immigration quota and renewing growth in Chinatown. With the quota totally lifted in 1968, growth exploded to the surrounding areas and almost completely engulfing Little Italy. Despite exploding real estate values and slow replacement of late 19th century buildings, the area still retained much of its third-world flavor into the 21st century. (reference)