Sec. 73.609  Zones.

    (a) For the purpose of allotment and assignment, the United States 
is divided into three zones as follows:
    (1) Zone I consists of that portion of the United States located 
within the confines of the following lines drawn on the U.S. Albers 
Equal Area Projection Map (based on standard parallels 29\1/2\ deg. and 
45\1/2\ deg.; North American datum): Beginning at the most easterly 
point on the State boundary line between North Carolina and Virginia; 
thence in a straight line to a point on the Virginia-West Virginia 
boundary line located at north latitude 37 deg.49' and west longitude 
80 deg.12'30'; thence westerly along the southern boundary lines of the 
States of West Virginia, Ohio, Indiana, and Illinois to a point at the 
junction of the Illinois, Kentucky, and Missouri State boundary lines; 
thence northerly along the western boundary line of the State of 
Illinois to a point at the junction of the Illinois, Iowa, and Wisconsin 
State boundary lines; thence easterly along the northern State boundary 
line of Illinois to the 90th meridian; thence north along this meridian 
to the 43.5 deg. parallel; thence east along this parallel to the United 
States-Canada border; thence southerly and following that border until 
it again intersects the 43.5 deg. parallel; thence east along this 
parallel to the 71st meridian; thence in a straight line to the 
intersection of the 69th meridian and the 45th parallel; thence east 
along the 45th parallel to the Atlantic Ocean. When any of the above 
lines pass through a city, the city shall be considered to be located in 
Zone I. (See Figure 1 of Sec. 73.699.)
    (2) Zone II consists of that portion of the United States which is 
not located in either Zone I or Zone III, and Puerto Rico, Alaska, 
Hawaiian Islands and the Virgin Islands.

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    (3) Zone III consists of that portion of the United States located 
south of a line, drawn on the United States Albers Equal Area Projection 
Map (based on standard parallels 29.50 and 45.50 North American datum), 
beginning at a point on the east coast of Georgia and the 31st parallel 
and ending at the United States-Mexican border, consisting of arcs drawn 
with a 241.4 kilometer (150 mile) radius to the north from the following 
specified points:

                                                                        
------------------------------------------------------------------------
                                                  North         West    
                                                latitude      longitude 
------------------------------------------------------------------------
(a).........................................        294000        832400
(b).........................................        300700        841200
(c).........................................        303100        863000
(d).........................................        304800        875830
(e).........................................        300000        903830
(f).........................................        300430        931900
(g).........................................        294600        950500
(h).........................................        284300        963930
(i).........................................        275230        973200
------------------------------------------------------------------------

    When any of the above arcs pass through a city, the city shall be 
considered to be located in Zone II. (See Figure 2 of Sec. 73.699.)

[28 1997 FR 13660 , Dec. 14, 1963, as amended at  33 FR 15422 , Oct. 17, 1968; 
 50 FR 23697 , June 5, 1985;  51 FR 44070 , Dec. 8, 1986]