The ABA area (sometimes referred to as the ABA Checklist Area) is essentially North America north of Mexico.
Specifically, the area encompassed is the 50 United States Canada, the French islands of St. Pierre et Miquelon, and adjacent waters to a distance of 200 miles from land or half the distance to a neighboring country, whichever is less.
Excluded by these boundaries are Bermuda, The Bahamas, and Greenland.
A subarea of the ABA Checklist Area, or other prescribed area, is as defined by its legal boundaries. If not legally defined otherwise, it includes adjacent water (rivers, lakes, bays, sounds, etc.) out to half the distance to a neighboring area, but not beyond 200 miles.
Birds observed on or over an ocean are counted for the area having jurisdiction over the nearest land, if within 200 miles.