Although accurate and relevant data about land are valuable in helping to answer many questions of public policy and private action, such data have not been generally available in the past. Most data about land have been fragmentary in the land uses included or in areas covered, or both; data series have typically been established to meet special purposes. The various concepts about land have often been confused; the areas of data summarization have typically been too large; and data collected at considerable expense have often not been kept current in spite of the fact that it would have been possible to do so, from records of current operations of local governments.