Consolidation
Motorized school buses in the 1920s made longer distances possible, and one-room schools were soon consolidated in most portions of the United States into multiple classroom schools where classes could be held separately for various grade levels. Gradually, one-room school houses were replaced. Most one-room schools had been replaced by larger schools by World War II except in the most rural areas. However, they are still common in rural parts of Australia.
Read more about this topic: One-room School