We argue that it is essential that the Astro2020 survey of the present state of American astronomy and the recommendations for the next decade address the issue of ensuring preservation of, and making more discoverable and accessible, the field’s rich legacy materials. These include both archived observations of scientific value and items of historical importance. Much of this heritage likely will be lost if action is not taken in the next decade. It is proposed that the decadal plan include recommendations on (1) compiling a list of historic sites and development of models for their preservation, (2) carrying out a comprehensive inventory of astronomy’s archival material, and (3) digitizing, with web-based publication, those photographs and papers judged to have the most value for scientific and historical investigations. The estimated cost for an example project on plate preservation is a one-time investment of less than $10 million over ten years plus the typical on-going costs to maintain and manage a medium sized database.