Furthermore, proximity to urban amenities such as transit stops has been shown to drive up home prices over time. A survey of Northwest Chicago conducted between 1975 and 1991 showed that homes located directly in the vicinity Red Line and Brown Line stops of the "L" rail transit system saw a huge price jump during these years, compared to only modest increases for area outside the zone. Between 1985 and 1991 in particular, homes near transit stops nearly doubled in value.