The area comprising the territory of Dakota shall, for the purposes of this act, be divided on the line of the seventh standard parallel produced due west to the western boundary of said territory; and the delegates elected as hereinafter provided to the constitutional convention in districts north of said parallel shall assemble in convention, at the time prescribed in this act, at the city of Bismarck; and the delegates elected in districts south of said parallel shall, at the same time, assemble in convention at the city of Sioux Falls.