The egg production sector has undergone radical change during the past 25 years. Iowa egg production prior to the 1960s was conducted through relatively small extensively managed flocks dispersed on diversified farming operations. Since that time new technologies have resulted in the industry moving rapidly to specialized intensively managed facilities in fewer locations. This trend can be seen in figure 1 showing the number of Iowa layer and 'pullet producers in 1964,1978 and 1987. The total number of producers in 1964 was about 72,000. By 1978 that total, had declined by more than 80% to about 11,000. Between 1978 and 1987 it fell by another 50% to less than 5,000.
Ginder, Roger G. and Owings, William J., "Layers, Pullets, and the Egg Production Sector" (1991). Economic Staff Paper Series. 227.