Under the People's Action Party, which came into power when it won the 1959 Elections of Singapore, the Housing Development Board was founded in 1960, replacing the Singapore Improvement Trust. This proved to be the turning point in the history of modern Singapore. Within five years, the HDB had constructed more than 50,000 housing units, which was several times more than the SIT had constructed within the time span of more than 20 years. Within the 1970s, most of the population had found adequate housing. Most of the current urban planning policy is derived from the practices of the HDB.