Gangs formed around similar ethnic backgrounds. After The Civil War there were Jewish, African American, Italian and Irish gangs in New York. Chinese gangs appeared in California in the mid 1800s. Philadelphia reported gangs as early as 1840. Between then and 1870 Philadelphia became home to over 100 street gangs. This is also the time when gangs started to use clothing for the sake of distinctiveness. Chicago became a type of gang capital during the 1920s, with a total of about 1,300 gangs and about 25,000 gang members. Immigration of Mexicans into California grew rapidly in this period. Many youngsters of the second generation didn't fit in the American society. They started wearing fancy and distinctive clothes called "Zoot Suits". Serious problems with sailors (it was the time of WW II) caused the "Zoot Suit Riots". Between 1941 and 1945 over half a million Puerto Ricans arrived in the United States. Most settled in New York City, which led to the formation of new gangs. Also during the 1920's the African American populations migrated from the south to northern cities and established gangs there.
Dressing, body language,