In the same sense, Medellín and its Metropolitan Area had to face the appearance of cartels during the 1970s, which produced serious problems of urban violence exacerbated by speedy urban growth and slow answers to the needs of the surrounding communities. The city grew due to big waves of migrants coming from the Colombian countryside looking for refuge from internal political conflict. This background explains why the young city would face urban violence with the same intensity as large metropolitan areas such as New York City, Mexico City or Rio de Janeiro and why the city had to create urban projects in answer to its conflicts and growth. The Medellín Metro was created not only as a massive urban transport solution for the working class residents of the city, but also as an important cultural symbol that would help develop marginalized sectors. The Metro would change the concept of public space in a city built for business and factories that had the systematic issue of lacking space for things like tourism.