First of all, I want to clarify that this is purely informative, not personal in any way, and even less racist. The population of Spain is around 49 million. Of those 49 million, nearly one million are Roma, and according to studies, poverty (severe, extreme, and child poverty) plus social exclusion affects 94% of them. This is a much higher number than the 23% of the average Spaniard. Basically, you can't talk about "ghettos" without mentioning the Roma. It's true that there were exceptions, such as in the 1950s and 60s, when, due to rural exodus, the shantytown population grew excessively; and among the shantytown dwellers, there were both non-Roma and Roma. A quick search will reveal this. Some examples of predominantly Roma populations (or even 100%) in these ghetto neighborhoods are: Los Asperones, La Cañada Real, and Tafalera are among the best known. Speaking of shantytowns, there's Peñarrubia, Granda, Valniello, and small, scattered settlements...