Malaria has been successfully eliminated or significantly reduced in certain areas. Malaria was once common in the United States and southern Europe, but vector control programs, combined with the monitoring and treatment of infected humans, eliminated it from those regions. Several factors contributed, such as the draining of wetland breeding grounds for agriculture and other changes in water management practices, and advances in sanitation, including greater use of glass windows and screens in dwellings. Malaria was eliminated from most parts of the United States in the early 20th century by such methods. The use of the pesticide DDT and other means eliminated it from the South's remaining pockets in the 1950s as part of the National Malaria Eradication Program.