- Every effort was made to accurately depict the rules. In certain instances an interpretation of the rules was made which may not necessarily reflect the legal position of the United States or Canada.
- This map is created in the NAD27 coordinate system, since the agreement between the United States and Canada was signed in 1965, and then projected to the NAD83 coordinate system to be consistent with the coordinate system required by the Commission’s Universal Licensing System (ULS).
- Download the shape files: LINE_ABCD_NAD83.zip
For bands below 470 MHz, the areas which are involved lie between Lines A and B and between Lines C and D, which are described as follows:
Line A - Begins at Aberdeen, Wash., running by great circle arc to the intersection of 48 degrees N., 120 degrees W., thence along parallel 48 degrees N., to the intersection of 95 degrees W., thence by great circle arc through the southernmost point of Duluth, Minn., thence by great circle arc to 45 degrees N., 85 degrees W., thence southward along meridian 85 degrees W., to its intersection with parallel 41 degrees N., thence along parallel 41 degrees N., to its intersection with meridian 82 degrees W., thence by great circle arc through the southernmost point of Bangor, Maine, thence by great circle arc through the southern-most point of Searsport, Maine, at which point it terminates; and
The definition of Line A in Section 90.7 is taken from Paragraph 2 of Arrangement A contained in the revised Technical Annex to the agreement between the United States and Canada on the "Coordination and Use of Radio Frequencies Above 30 Megacycles per Second", signed at Ottawa on June 16 and 24, 1965. As you indicate, some points on the line are defined as passing through certain points of cities. These points have been interpreted differently by various persons who have attempted to draw, or enter into a computer, points along this line. As you have noted, there are at least three sets of points used for the four cities listed. Because these points are subject to interpretation, it would be difficult to argue which set is correct; however, for the sake of consistency, it would be desirable that the same set of points be used by everyone.
A review of detailed maps indicates that the first of the three sets listed in your memorandum is the most accurate (assuming a typographical error in the minutes of longitude for Duluth) and is close to that used by the National Telecommunications and Information Administration (NTIA). In order that all agencies of the Federal Government are defining Line A in the same way, we would recommend that we adopt the same points as used by NTIA. They are as follows:
| Searsport ME | Bangor ME | Duluth MN | Aberdeen WA |
| 44-27-00 | 44-46-00 | 46-36-00 | 46-58-00 N |
| 68-55-00 | 68-47-00 | 92-10-00 | 123-50-00 W |
You may wish to note that NTIA is using the following points for defining each end of the line:
| Easternmost Point |
Westernmost Point |
| 44-00-00 | 46-37-00 N |
| 68-40-00 | 125-00-00 W |
We recommend that these end points be used or that the line segments be extended, if necessary, in the same direction from the above end points.
Line B - Begins at Tofino, B.C., running by great circle arc to the intersection of 50 degrees N., 125 degrees W., thence along parallel 50 degrees N., to the intersection of 90 degrees W., thence by great circle arc to the intersection of 45 degrees N., 79 degrees 30 W., thence by great circle arc through the northernmost point of Drummondville, Quebec (lat: 45 degrees 52 N., long: 72 degrees 30 W.), thence by great circle arc to 48 degrees 30 N., 70 degrees W., thence by great circle arc through the northernmost point of Campbellton, N.B., thence by great circle arc through the northernmost point of Liverpool, N.S., at which point it terminates.
Line C - Begins at the intersection of 70 degrees N., 144 degrees W., thence by great circle arc to the intersection of 60 degrees N., 143 degrees W., thence by great circle arc so as to include all of the Alaskan Panhandle; and
Line D - Begins at the intersection of 70 degrees N., 138 degrees W., thence by great circle arc to the intersection of 61 degrees 20 N., 139 degrees W., (Burwash Landing), thence by great circle arc to the intersection of 60 degrees 45 N., 135 degrees W., thence by great circle arc to the intersection of 56 degrees N., 128 degrees W., thence south along 128 degrees meridian to Lat. 55 degrees N., thence by great circle arc to the intersection of 54 degrees N., 130 degrees W., thence by great circle arc to Port Clements, thence to the Pacific Ocean where it ends.