The latter 20th century is marked by population growth, especially in the borough's north end. In 1963, an extension of the Anillo Periférico ring road was constructed through the borough. The road brought people and prompted the development of housing projects in the 1970s for the city’s growing population. These developments include Santa Teresa, Pedregal II, Pueblo Nuevo, Potrerillo, El Rosal, El Tanque, and El Toro, heading west from the roadway. In 1900, the area was completely rural, with a population of only 8,150 people mostly located in the town of La Magdalena. The borough's population began growing quickly in the 1940s to over 40,000 in 1960, but by 1990 the population had reached over 195,000. Population growth continues but at a slower pace: 222,000 by 2000 and 229,000 in 2005. There is limited space for housing projects due to the geography of the area but population growth has prompted illegal settlements in conservation areas and in steep ravines where landslides are a danger.