The Dust Bowl was a period of severe dust storms that damaged the environment and agriculture in the central United States and Canada from the 1930s. Farmers had plowed up the native grasses and over-planted crops, leaving the topsoil exposed and vulnerable to wind erosion when a prolonged drought hit. Without vegetation and during sustained high winds, the topsoil was blown away, creating massive dust storms that killed crops and exposed the land, which could no longer support agriculture. Millions were displaced as the land became unusable. The federal government later created programs to encourage sustainable farming practices to help rehabilitation.