- Some MPOs were entirely defined by county units. The NTAD county layer served as the basis for bringing in the county(s) and merging several counties if necessary into the MPO shapefile. - Some MPOs sent shapefiles or other digital files with the boundary. The projection needed to be defined before inclusion into the dataset. As the projection information was not included in many cases, some errors could have been introduced and calls or email were required to the contact person for the data. NAD83 datum was assumed and tested for agreement on occasions where the datum could not be verified. - Some digital files had multiple polygons that were merged to form a single multipart polygon in ESRI format. - Some digital files were converted using ESRI and other proprietary tools to ESRI readable formats and then added to the MPO shapefile. Others were converted to ESRI readable files with request to the MPOs themselves or BTS. - Some digital files arrived as line features and built using ESRI tools to form polygons. On some occasions small connectors were added to complete the topology of the polygon (usually not more than a few meters). - On occasions where the boundaries received were significantly out-of-alignment with the NTAD county layer, but clearly intending to follow a county boundary in a particular boundary region, part of the received boundary would be snapped to the NTAD county boundary layer. This snapping occured frequently along shorelines or rivers. These adjustments were an attempt to create uniformity with the NTAD county boundaries. - In the few digital sources that were not referenced to a coordinate system, ESRI affine transformation tool and manual creation of reference points were used to bring the data into a known coordinate system. - In the few text descriptions of boundaries received from MPOs (rather than digital files), geographies were used from several sources to manually create the boundaries. The sources are noted in the Source Information section of this document. - For MPOs with no boundary information, 5 mile radius circular placeholders were created using a North American Lambert Conformal Conic Projection with Incorporated Places/Census Designated Places, 2000, for placement reference.