This entry contains information applicable to United States law only. The process by which legislative seats are distributed among units entitled to representation. Determination of the number of representatives that a state, county, or other subdivision may send to a legislative body. The U.S. Constitution provides for a census every ten years, on the basis of which Congress apportions representatives according to population; but each state must have at least one representative. "Districting" is the establishment of the precise geographical boundaries of each such unit or constituency. Apportionment by state statute that denies the rule of one-person, one-vote is violative of equal protection of laws.
Also, the allocation of a charge or cost such as real estate taxes between two parties, often in the same ratio as the respective times that the parties are in possession or ownership of property during the fiscal period for which the charge is made or assessed.
Who are to be the electors of the Federal Representatives? Not the rich more than the poor; not the learned more than the ignorant; not the haughty heirs of distinguished names, more than the humble sons of obscurity and unpropitious fortune. The electors are to be the great body of the people of the United States (James Madison, The Federalist No. 57)
The difference most relied upon, between American and other republics, consists in the principle of representation (James Madison, The Federalist No. 63)
James Madison and his fellow founders of the United States of America sought many objectives as they framed the U.S. Constitution. Among the goals these champions of democracy fought for was the notion of equal representation in government, by congresspeople, for citizens of the United States. To ensure that equal representation occurred, the founders proposed that the U.S. population be counted at regular intervals with a census. They later agreed, in the Great Compromise of 1787, that congressional representation should be assigned — in other words, apportioned — to various regions of the country based on a total population standard. Both article 1, section 2, clause 3, and amendment 14, section 2, of the Constitution provide that representatives shall be apportioned among the states according to their respective numbers and that a population count will be taken by census every ten years. Apportionment requires that each state's total population be divided by the population of "the ideal district" to determine the appropriate number of representatives. The population of an ideal district, for purposes of federal apportionment, is defined as the total population of the state (as determined by census) divided by one hundred (for the House of Representatives), or by fifty (for the Senate).
In the centuries that have followed the United States' adoption of the Constitution, apportionment for the federal Congress has been based on total population — with the exception that a slave, until the Civil War, was considered property and thus counted only as three-fifths of a white person. Efforts to limit federal congressional apportionment to only people who are citizens or voters have been defeated, because the exclusion of groups such as illegal aliens, nonvoters, and children could significantly affect some areas of the country, since some states have large populations of these groups. Shifting political power away from an area means fewer legislators to demand a fair share of government resources for that area. One such effort to exclude these groups, which occurred during the 1866 debates over the passage of the Fourteenth Amendment, ultimately led to Congress's voting to continue basing apportionment on total population and to count the "whole number of persons in each state." In contrast, state legislatures have only been required to be based substantially on population since 1964 (Reynolds v. Sims, 377 U.S. 533, 84 S. Ct. 1362, 12 L. Ed. 2d 506). In 1968, the U.S. Supreme Court extended this requirement to municipal governments as well (Avery v. Midland County, 390 U.S. 474, 88 S. Ct. 1114, 20 L. Ed. 2d 45).
Apportionment is related to, but is not the same as, the electoral system and the districting process: apportionment is the manner in which representation is distributed; the electoral system is the way an individual representative is elected; and the districting process establishes the precise electoral boundaries of a representative's district. Apportionment for the U.S. Congress, which consists of the Senate and the House of Representatives, has always been determined by the Constitution. Each state is assigned two senators, who were originally elected by state legislatures but have since the adoption of the Seventeenth Amendment in 1913 been chosen by direct voter election.
Membership in the House of Representatives is also assigned to the states and is apportioned according to population, with each state being constitutionally guaranteed at least one representative. The House of Representatives grew proportionally with the population of the United States until 1912, when the House froze its size at 435 members. Since 1941, the Bureau of the Census has used the system of equal proportions to determine how many of the 435 representatives each state is entitled to have. This method, developed in 1920 by Professor Edward V. Huntington, of Harvard University, establishes the smallest possible difference between the representation of any two states, since a state's fair share of representatives will rarely be a whole number. The 1941 federal statute 2 U.S.C.A. §§ 2a and 2b provides that
under the "equal proportions" method, the priority list of states or counties among which Representatives in excess of one per state or county are to be allocated is obtained by dividing the population of each state or county by the geometric mean of successive numbers of Representatives.
Congress must decide how to treat the fractional components whenever it reapportions congressional seats based on new census data. This decision affects the distribution of only a few seats in Congress and the electoral college, but in closely contested matters, such as the presidential election of 1876, those seats could mean the difference between victory and defeat. (The electoral college is the body of electors of each state chosen to elect the president and vice president. Apportionment affects the electoral college because it influences the number of electoral votes coming from various areas of the country.) Each state legislature is responsible for establishing the district boundaries of the congressional seats apportioned to the state by the federal government.
From 1842 to 1911, Congress required that all congressional districts be of compact and connecting territory. That stipulation was not continued after 1912, and by the 1960s, the districts within some states differed greatly in size. These disparities were caused in some cases by gerrymandering, which is the process of drawing boundaries for election districts so as to give one party a greater political advantage. Large disparities led a group of urban Tennessee voters to bring suit against their state's electoral commission on the ground that the apportionment of the legislature was unfair. The Supreme Court's March 1962 decision in favor of the voters in Baker v. Carr, 369 U.S. 186, 82 S. Ct. 691, 7 L. Ed. 2d 663, established the rule that a citizen may bring suit against legislative malapportionment when it deprives that citizen of equal protection under the law as guaranteed by the Fourteenth Amendment. Previously, in Colegrove v. Green, 328 U.S. 549, 66 S. Ct. 1198, 90 L. Ed. 1432 (1946), the Court had refused to accept jurisdiction in apportionment cases.
Although the Supreme Court's decision in Baker was limited, it did rule that if a system other than one based on population is used for apportionment, the resulting districts must not be arbitrary or irrational in nature. In 1964, the Supreme Court extended Baker by ruling in Wesberry v. Sanders, 376 U.S. 1, 84 S. Ct. 526, 11 L. Ed. 2d 481, that legislative districts for the House of Representatives must be drawn so as to provide "equal representation for equal numbers of people," a concept often referred to as the "one-person, one-vote" standard. Later that same year, in lawsuits directly involving fifteen states, the Supreme Court ruled in Reynolds v. Sims, 377 U.S. 533, 84 S. Ct. 1362, 12 L. Ed. 2d 506, that districts for state legislatures must also be substantially equal in population. Further extending the principle, the Court ruled in Avery v. Midland County, 390 U.S. 474, 88 S. Ct. 1114, 20 L. Ed. 2d 45 (1968), that if county, city, and town governments elect their representatives from individual districts, the districts must be substantially equal in population.
Other individuals and states have subsequently challenged the method of apportionment used in the United States when that method has proved unfavorable for them. For example, in Franklin v. Massachusetts, 505 U.S. 788, 112 S. Ct. 2767, 120 L. Ed. 2d 636 (1992), Massachusetts and two of its registered voters filed an action against U.S. Secretary of Commerce Barbara B. Franklin, alleging, among other things, that the decision to allocate overseas employees was inconsistent with the Constitution. In June 1992, the Court reversed a federal district court decision in favor of Massachusetts, ruling that the allocation of overseas federal employees to their designated home states was consistent with the "usual-residence" standard used in early censuses and served the purpose of making representation in Congress more equal.
The state of Montana also sued the U.S. Department of Commerce, following the 1990 census, when it and eleven other states each lost one House seat. In seeking to keep the two seats it had held since 1910, Montana argued that the method of equal proportions was unconstitutional because it left the state with a single congressional district of 803,655 people — a number almost 40 percent larger than "ideal district size," which is a national average of 572,466 people. Montana also alleged that the variance between the single district's population and that of an ideal district could not be justified under the one-person, one-vote standard developed in Wesberry. The Montana case was appealed to the U.S. Supreme Court, which in March 1992 unanimously upheld the method Congress uses to reallocate congressional seats among the states after a census (United States Department of Commerce v. Montana, 503 U.S. 442, 112 S. Ct. 1415, 118 L. Ed. 2d 87).
See: Baker v. Carr; Congress of the United States; Electoral College; Equal Protection; Fourteenth Amendment; Gerrymander; Reynolds v. Sims.