Workers in a bureaucracy understand what is expected of them because of a system of

Workers in a bureaucracy understand what is expected of them because of a system of : Formalized rule 
Which means that the workers usually only have a specific predetermined task that they're allowed to do within the system

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Mining manufacturing

The changes to agriculture in the united states since 1900 is that increased mechanization has increased food production, thereby increasing the need for labor. there has been an increased need for higher speeds of food production due the fact that the population in the united states continues to rise.