§8. In order to keep the representation throughout the state as nearly
equal as possible; in other words, to secure to the people of every
county or district their just proportion of the representatives, the
constitution requires that, at stated times, the people of the state
shall be numbered, and a new apportionment of senators and
representatives be made among the several counties according to the
number of inhabitants in each county; or if the state is one in which
members of the legislature are chosen in districts, a new division of
the state is made into districts.

§9. But the periods of time between the enumerations of the people, are
not the same in all the states. In some states the enumerations are made
every ten years; in others, shorter periods have been fixed, from eight
down to four years. This enumeration or numbering of the people is
called taking the census. _Census_ is from the Latin, and was used by
the ancient Romans to signify a declaration or statement made before the
censors by the citizens, containing an enumeration or register of
themselves, their wives, children, servants, and their property and its
valuation. In the United States, although the census sometimes includes
a similar register, the word usually means simply an enumeration of the
people.

§10. The constitution also prescribes the qualifications of senators and
representatives. If, as qualifications for an elector, full age,
citizenship, and a considerable term of residence in the state and
county, are properly required, as we have seen, (Chap. VI. §2-5,) they
must be at least equally necessary for those who make the laws. In no
state, therefore, are any but qualified electors eligible to the office
of senator or representative. In some states, greater age and longer