Hip Hop is a cultural movement born in the Bronx in the first half of the 1970s. The Bronx is one of the five administrative districts of New York, which went down in history in that period for having been the victim of notable urban decay, which brought the neighborhood to a very high rate of poverty and unemployment, favoring the increase of criminal activity and the birth of different “gangs”.
Among the first events that led to the impoverishment of the Bronx we find the construction in 1959 of the “Cross-Bronx Expressway”, a large road that runs through the neighborhood, during whose construction brought at the demolishing of houses, warehouses and factories. This meant the loss of jobs for a good part of the habitants of that area, and pushed the white middle class to move in other neighborhood, in search of greater economic security and a more comfortable lifestyle: this resulted in a strong devaluation of real estate assets, which it pushed many African Americans to move to the Bronx attracted by the cheaper rents compared to other neighborhoods of the city.
As the 1980s approached, the Bronx began to face a phase of regrowth and the ruling class became interested in the redevelopment of the neighborhood by investing 1 billion dollars in the construction of new residential structures. But it was the birth of HipHop that brought real positive change to this neighborhood. The younger boys, who grew up in a context of extreme poverty and marked by the death of friends and family decided to establish a truce between the gangs, favoring peaceful coexistence rather than violence: this new climate favored integration and cultural exchange between the various ethnic groups residing in the neighborhood, mainly African Americans and South Americans, laying the foundations for the birth of “block parties”, real neighborhood parties based on music and dance.
Towards the end of the 1980s and the beginning of the 1990s, started a period called ”the Golden Age”, and like we can imagine it is called like this because is the period of maximum expansion all over America.
The nineties saw the explosion of the Hip Hop phenomenon in sales and the confrontation between the East Coast and the West Coast, two worlds at odds in the rap scene which have never hidden their rivalry, even resulting in tragic outcomes (the deaths by Tupac Shakur and Notorious BIG in 1996 and 1997).

Between the end of the nineties and the early 2000s, under the aegis of Dr. Dre, new rappers such as Eminem contributed to further increasing the popularity of Hip-Hop. The first decade of the 21st century was also one with various mixes with commercial pop; rap, in fact, often made inroads into the albums of the most famous pop stars. But precisely this popularity generated an opposite effect at the end of the decade and a rediscovery of the “alternative genre” thanks to rappers like Kayne West, Drake or Kid Cudi

Sources
https://www.britannica.com/art/hip-hop