Following world war 1, which industry experienced tremendous growth in the 1920s.

After WW1 it took a while for life to go back to normal. Everyone around this time were creating new ideas and which lead to mass production. The demand for the multitude of new product was higher then ever and they thought that they were getting somewhere. However the prosperity of the 20s was not universal, many places were still dependent on farming. But everything went downhill and it led to the great depression 

Independent executive agencies are more specialised.