 West Palm Beach became the nation's fourth fastest growing metropolitan areas during the 1950s; the city's borders spread west of Military Trail and south to Lake Clarke Shores.Between 1949 and 1962, property values rose from $72 million to $147.5 million, while the population in 1950 was 43,612 and increased about 30% by 1960.In 1955, using a $18 million bond issue, the City of West Palm Beach upgraded its sewer system and purchased the water treatment plant (then owned by Henry Flagler's estate) and land to the west of the city's boundaries, including of wetlands (from Flagler Water Systems) and an additional of land previously owned by Flagler's Model Land Company.