Waves of new arrivals into Taipei, starting in the later 1940s and continuing in the 1970s and 1980s, combined with the dramatic increase in land prices in the 1980s and 1990s, led to illegal expansion and construction of houses everywhere, so that now illegal structures are a normal part of Taipei life.
戰後國民政府撤退帶來的逃難人潮在鐵路旁、公共用地上搭違建。接著第二波、第三波，七○年代城鄉移民也佔領許多空地。八○、九○年代地價狂飆，造成小坪數住家合法購買、違法擴建。到今天，看不到違建，已經「不算台北」。