Vital Statistics, which basically refer to the births, marriages and deaths occurring within the Spanish territory, constitute one of the most traditional statistical operations in the National Statistics Institute. The first volume was published in 1863 by the National General Board of Statistics, and contains data on the period from 1858 to 1861, which was obtained from parish registers. Since that time, information has consistently been published in Spain regarding these demographic phenomena, with the sole interruption during the period from 1871 to 1885, the time when the Civil Register was implemented, and from which data was subsequently obtained for these statistics. The administrative source of the data in the Vital Statistics is the Civil Register. The observation units are the births, marriages and deaths registered in the books of the Civil Register.