Gangs are involved in all areas of street-crime activities like extortion, drug trafficking, both in and outside the prison system, and theft. Gangs also victimize individuals by robbery and kidnapping. Cocaine is the primary drug of distribution by gangs in America, which have used the cities Chicago, Cape Town, and Rio de Janeiro to transport drugs internationally. Brazilian urbanization has driven the drug trade to the favelas of Rio. Often, gangs hire "lookouts" to warn members of upcoming law enforcement. The dense environments of favelas in Rio and public housing projects in Chicago have helped gang members hide from police easily.