Population Research and Policy Review 18: 507–524, 1999.
© 1999 Kluwer Academic Publishers. Printed in the Netherlands.
The impacts of apportionment method, and legal and illegal
immigration, on Congressional apportionment in the year 2000
DUDLEY L. POSTON, JR.
, LEON F. BOUVIER
& HONG DAN
Texas A&M University;
Abstract. This paper ﬁrst discusses two methods for apportioning the US House of Represen-
tatives, Equal Proportions and Major Fractions. The method of Equal Proportions will be used
in the 2000 apportionment, but it is biased in favor of smaller states. The method of Major
Fractions is a mathematically unbiased method, but will not be used in 2000. However, we
show that apportionments for 2000 would not differ much according to these two methods. We
also consider different deﬁnitions of the apportionment population, mainly based on including
or excluding legal and illegal immigrants from the apportionment process. We show that the
apportionment results for 2000 will not differ if illegal immigrants who entered the USA in
the 1990s are kept in, or removed from, the apportionment population. But the apportionment
results will differ in a major way if all persons immigrating to the USA in the 1990s are kept
in, or removed.
Keywords: Census, Apportionment, Constitution
On 1 April 2000 the US government will conduct our 22nd decennial census;
the ﬁrst census was undertaken in 1790, and censuses have been taken every
ten years since. Providing to the President an empirical basis for apportion-
ing the US House of Representatives is the principal reason and justiﬁcation
for conducting a decennial census. Indeed the requirement for a decennial
census was written into the US Constitution in 1787; “Representatives and
direct taxes shall be apportioned among the several states which may be
included within this Union according to their respective numbers .... The
actual enumeration shall be made within three years after the ﬁrst meeting
of the Congress of the United States, and within every subsequent term of
ten years in such manner as they shall by law direct” (The US Constitution,
Article 1, Section 2).
However, the US Constitution does not specify the method for apportion-
ing the Congress, not does it specify how the population to be apportioned
should be composed. Several very different apportionment methods have
been used to apportion the Congress since our country’s ﬁrst apportionment in
1790. The apportionment of 2000 will use the method of Equal Proportions,