The origin of the Rollin' 30s Harlem Crips can be traced to 1961, when a hurricane flattened Belize City. As a result Belizeans emigrated to South Los Angeles and formed large communities. South Los Angeles was already home to street gangs like the Crips and the Bloods. Overcome by poverty and not only in part thanks to the common cultures of African Americans and Belizean Creole people, some Belizeans became members of the larger gangs. Following a wave of gang violence, ethnic Belizean gang members were deported back to their country of origin. Deported Belizean gang members quickly spread the culture of Bloods and Crips in Belize City. It is alleged that the name Rollin' 30s Crips already originated in Belize. In the 1990s Belizeans also emigrated to New York City, many of them in Harlem. Among these expatriates were people who were involved in street gangs in their home country. In turn Harlem was the birthplace of the Rollin' 30s Harlem Crips, which largely drew its membership from large Belizean immigrant families. Expatriate countrymen in cities like Los Angeles also heard about the formation of the gang and soon it spread throughout the nation.
While every Crips street gang has members that are more likely to be involved in street crime, a disproportionate amount of the Harlem Crips members are known for being more businesslike and ambitious making the gang an overwhelmingly organized crime group. The opportunities for organized crime were and still are a direct result of the situation in Belize. Colombian cartels use Belize as one of their major routes to move cocaine and heroin to the USA. Colombian narcotraffickers do business with gang bosses in Belize who in turn use their connections with expatriate Belizean gang members in cities like New York and Los Angeles. The Rollin 30's Harlem Crips being an overwhelmingly Belizean gang, they are able to being involved in drug trafficking on a higher level. Other criminal activities include weapon trafficking, prostitution, murder and robbery.