There is more information in here about vital records in the United States than most genealogists will need, but the  U.S. Vital Statistics System: Major Activities and Developments, 1950-95, 
by the Centers for Disease Control and Prevention/National Center for Health Statistics provides significant background on the development of vital statistics (birth, marriage, and death) registration in the United States. It also includes a reprint of historical information regarding vital statistics in the United States before 1950.

It includes how the content of the standard birth and death certificates have changed in the United States, when states began registration of vital events, etc.