For the purpose of electing senators in 1967 and until the 1970 decennial census of the United States for New Jersey shall have been received by the Governor, the forty senators are hereby allocated among fifteen Senate districts, as follows: First District - the counties of Gloucester, Atlantic and Cape May, two Senators; Second District - the counties of Salem and Cumberland, one senator; Third District - the county of Camden, three senators; Fourth District - the counties of Burlington and Ocean, two senators; Fifth District - the county of Monmouth, two senators; Sixth District - the county of Mercer, two senators; Seventh District - the county of Middlesex, three senators; Eighth District - the county of Somerset, one senator; Ninth District - the county of Union, three senators; Tenth District - the county of Morris, two senators; Eleventh District - the county of Essex, six senators; Twelfth District - the county of Hudson, four senators; Thirteenth District - the county of Bergen, five senators; Fourteenth District - the county of Passaic, three senators; and Fifteenth District - the counties of Sussex, Warren and Hunterdon, one senator.