What is metadata, and do the historical topo maps have it?

Metadata is defined by the Federal Geographic Data Committee as "the background information which describes the content, quality, condition, and other appropriate characteristics of the data. Paper maps contain metadata, primarily as part of the map legend. In this form, metadata is readily apparent and easily transferred between map producers and map users. When map data are in a digital form, metadata is equally as important, but its development and maintenance often require a more conscious effort on the part of data producers and the chain of subsequent users who may modify the data to suit their particular needs."

The historical topo maps collection has gathered all dates and other relevant information from the printed maps and included the data in a metadata file for each map. An XML metadata file is included with each map as an attachment. Also, a CSV database dump of selected metadata fields for the complete HTMC and US Topo collections is refreshed nightly and posted here.