One of my medium-to-long-term objectives is to create a series of standard layers which could act as the starting point for value-added datasets as well as supply base map features. Because I am drawing from a variety of sources, each using different data acquisition techniques, storage formats, specifications and standards there will inevitably be inconsistencies between layers that need to be reconciled. For example Natural Earth (http://www.naturalearthdata.com/) is the go-to resource for downloads if you need to display boundaries, coastlines and major water bodies at continental scales. This site also supplies administrative boundaries immediately below the national level (i.e. provinces or states) – but not anything as small as counties or municipalities. For that you typically have to go to a government sponsored website that distributes their own geographic data – or buy commercial data – or extract the layer from OpentStreetMap or other free provider. You now have two or more layers (e.g. Canadian Provinces from Natural Earth and Canadian Municipal Boundaries from government sources) that theoretically nest inside each other but probably won’t.