There are many similarities between building a geospatial digital archive and building a hard-copy map collection, and two major ones are the necessity to have a collection development policy and the amount of hard work required to seek out and acquire the resources. Two institutions, University of California at Santa Barbara and Stanford University, the initial partners in the National Geospatial Digital Archives (NGDA), chose to collect digital data that was in line with each library's standard collection strengths and responsibilities. Collection development policies were written for the project as a whole and for each partner institution. While based on traditional paper map policies, these geospatial collection development policies are tailored specifically for digital data by including sections on metadata, versioning, file formats, proprietary formats, data set size, and ownership/access considerations.
During the acquisition phase of the contract a considerable amount has been learned about file formats, data acquisition of compressed vs. uncompressed files, short-term storage prior to repository ingest, and metadata creation. While metadata creation at the collection-level/series-level has been relatively easy the acquisition phase has underscored the challenges inherent in creating accurate item-level metadata. One of the central findings of the NGDA experience is that format information is vital for long-term preservation. Thus, the need to understand file formats and specifications has led to the creation of a format registry specifically for geospatial materials.