Every 10 years, through the apportionment and redistricting processes within each state, Congress and the states attempt to create a U.S. House of Representatives that reflects a fair representation of the people of the United States. It is, generally, a complex, volatile, and highly political process, but one that, with a single exception, has occurred in various forms for over 200 years (since 1790), and, for some, represents, along with free elections, the clearest indication that the United States is a representative democracy. U.S. congressional districts (currently set at 435) are reallocated among the 50 states based on population counts from the national census taken at the beginning of each decade. Once the reapportionment of seats among the states is complete, congressional district boundaries are subject to change by state governments in all states with more than one district. The goals of the redistricting process within states are that each congressional district shall be represented by a single Member; nearly equal in population within each state; and moderately unequal in population among states. The U.S. Constitution (Article 1, Section 2 as amended by the 14 th Amendment, Section 2) requires that "representatives shall be apportioned among the several states according to their respective numbers, counting the whole number of persons in each state, excluding Indians not taxed." The requirement that districts must be apportioned among states means district boundaries cannot cross state lines. The Constitution, also in Article 1, Section 2, sets a minimum size for the House of Representatives (one Representative for each state) and a maximum size for the House (one Representative for every 30,000 persons). Congress is free to choose a House size (with the concurrence of the President) within these boundaries. The single-member district is now the norm in the United States House of Representatives. States with more than one Representative are divided into districts that are each represented by one Member. There have been exceptions to this practice, especially prior to 1842, when a number of states elected Representatives on a "general ticket" or "at-large" basis by having them listed on a statewide ballot. The United States has also implicitly rejected the concept of proportional representation by party for Congress by adopting the single-member district standard. Once districts are allocated among the states based on population (apportionment), the actual redrawing of district lines (redistricting) is carried out by each state. This process is usually completed by the state legislatures, but a number of states provide for nonpartisan or bipartisan commissions to draft the plans. Although the technology has changed, the process of redistricting in the 21 st century is likely to be much the same as it was in the 20 th century. Line-drawers use information from the census (and other data, such as voting patterns and voter registration figures) to plot district boundaries on maps. As legal requirements have changed and technology has improved for analyzing data, many districts are created using smaller and more complicated geographic units or entities. Rather than using whole counties, cities, towns, or other natural geographic features to delineate districts as in the past, line-drawers now use geographic units created by the Census Bureau for statistical purposes. These "census tracts" and the smaller "blocks" are used because, as very small geographical units, they facilitate the precision necessary to make districts absolutely equal in population. During the 1980s and 1990s the redistricting process moved from calculators and paper maps to computerized databases and mapping software. Whereas pre-1980s technology limited the number of competing plans that could be drawn, computerized redistricting often increased the number of plans that were presented to districting bodies in the states. During this period, however, the immense size of computerized map and census data files tended to limit participation of groups outside state government to those with relatively sophisticated computer technology. Today, with the advancement of personal computer technology as well as access to relatively inexpensive advanced geographic information systems (GIS) computer software, a variety of groups and individuals are capable of producing sophisticated district maps and participating in the redistricting process depending on state laws and procedures. Congressional redistricting traditionally has been a state function, but the federal government has intervened in the process through statutory law and judicially imposed rules stemming from challenges to state-crafted plans. Currently, the redistricting process is dictated by a set of federal court rulings, federal statutory laws, state constitutions, state laws, and state court rulings. The following "rules" may constrain the drawing of the boundaries of congressional districts (and, to a large extent, state legislative district boundaries as well): 1. equality of population size for districts within each state with two or more districts—U.S. Constitution, Article I, Section 2; 2. protection of the rights of racial and language minorities against vote dilution—Voting Rights Act of 1965 as amended, 42 U.S.C. Section 1973c; 2a. race cannot be only factor used in districting—U.S. Constitution, 14th Amendment, Section 1, the "equal protection clause"; 3. geographic compactness of districts—(17 states require this in congressional districting); 4. contiguity of districts—(22 states require this in congressional districting); 5. preservation of the boundaries of political subdivisions (minimize the splitting of county and towns boundaries between congressional districts)—(18 states require this in congressional districting); 6. maintenance of "communities of interest"—(13 states require this in congressional districting); 7. protection of political incumbents—(7 states allow for this in congressional districting, but 5 states prohibit this. ); 8. maintenance of current political representation by preserving the "core" of congressional districts—(7 states require and 3 states allow for this in congressional districting); and 9. the promotion of electoral competition or prohibition of partisan considerations within congressional districts—(7 states require this in congressional districting). , While the U.S. Constitution clearly authorizes the apportionment of the seats of the House of Representatives based on population counts, there is little or no guidance as to how this apportionment actually is to be accomplished, much less anything about the redistricting process. Presently, congressional redistricting is governed primarily by judicial interpretation of fundamental constitutional rights, rather than by federal statutory law (with the exceptions of Voting Rights Act standards and the law requiring that Members of Congress be elected from districts) and by state constitutional and statutory laws. This was not always true. Congressionally imposed standards providing that districts be compact, contiguous, and essentially equal in population existed throughout most of the 19 th and early 20 th centuries, until 1929. Congress first passed federal districting standards in 1842, when it added a requirement to the Apportionment Act of that year that Representatives "should be elected by districts composed of contiguous territory ... no one district electing more than one Representative" (5 Stat. 491). The Apportionment Act of 1872 added another requirement to those first set out in 1842, saying that districts should contain "as nearly as practicable an equal number of inhabitants" (17 Stat. 492). A further requirement of "compact territory" was added when the Apportionment Act of 1901 was adopted, stating that districts must be made up of "contiguous and compact territory and containing as nearly as practicable an equal number of inhabitants" (26 Stat. 736). Although these standards were never enforced if the states failed to meet them, this language was repeated in the 1911 Apportionment Act and remained in effect until the adoption in 1929 of the Permanent Apportionment Act, which did not include any districting standards (46 Stat. 21). After 1929, there were no congressionally imposed standards governing congressional districting until 1967, when the requirement that Members be elected from geographically based districts, rather than elected from at-large statewide positions, was re-imposed (81 Stat. 581, codified at 2 U.S.C. 2c). Malapportionment is the term used to describe the lack of equal representation by population within a state. Malapportioned congressional districts have existed in the United States since the First Congress, with the degree of malapportionment varying over time. The series of court cases beginning in 1962 with Baker v. Carr (369 U.S. 186) relating to political equality were attempts at minimizing malapportionment in congressional and state legislative redistricting (see below). As noted above, the purpose of the apportionment and redistricting processes is to create "fair" representation. The "rules" for redistricting (see below for a discussion) are, in part, meant to assist (or constrain) in this process and to minimize "the deliberate manipulation of district boundaries to enhance the electoral prospects of a particular political interest." In general, "enhancing the electoral prospects of a particular political interest" is often referred to as gerrymandering, combining the name of Massachusetts Governor Elbridge Gerry with the term "salamander," describing the shape of the boundaries of a state legislative district drawn to favor Gerry's political party in the 1800-1812 redistricting cycle. While some consider any construction of district boundaries to be, by its very nature, gerrymandering, the term usually implies an attempt to manipulate district boundaries to favor one's own group interests. This is usually accomplished using two techniques: "packing" and "cracking." "Packing" occurs when potential voters with similar expected voting behavior (e.g., Democrats, Republicans, African Americans, Hispanic Americans, etc.) are deliberately concentrated into fewer congressional districts. "Packing" of more than a majority of any such group into a congressional district creates "wasted votes," as it only takes 50% plus one vote to elect a preferred candidate in the American system of single-Member, winner-take-all congressional elections.