This macro will identify contiguous sets of polygons. It marks each polygon with the lowest ID number from among the contiguous group of polygons to which it belongs. The polygons can then be merged into districts using the "Merge By Value" function in the Maptitude GUI.
Free and open source (GPLv3 license).
As early as April 2014, NOAA will discontinue printing its lithographic nautical charts in favor of its increasingly popular digital versions, saving the organization millions of dollars in printing and updating. Directions Magazine interviewed Ted Florence, president of Avenza Systems, about the move to digital.