§  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 291/2 ° and 451/2 °; 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°49' and west longitude 80°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°
   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° 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 § 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.

   (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 latitude West longitude
   (a)     29°40'00''     83°24'00''
   (b)     30°07'00''     84°12'00''
   (c)     30°31'00''     86°30'00''
   (d)     30°48'00''     87°58'30''
   (e)     30°00'00''     90°38'30''
   (f)     30°04'30''     93°19'00''
   (g)     29°46'00''     95°05'00''
   (h)     28°43'00''     96°39'30''
   (i)     27°52'30''     97°32'00''

   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 § 73.699.)

   [ 28 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]