The following is a brief discussion of basic legal requirements relating to redistricting. For more information on the legal requirements, see State and Federal Law Governing Redistricting in Texas . This discussion does not include judicial redistricting, which is substantially different from redistricting of districts for legislative bodies.
The federal constitution calls for reapportionment of congressional seats according to population from a decennial census (Section 2, Article I). Reapportionment is the division of a set number of districts among established units of government. For example, the 435 congressional seats are reapportioned among the 50 states after each decennial census according to the method of equal proportions. The boundaries of the congressional districts are then redrawn by state legislatures in accordance with state and federal law.
Redistricting is the revision or replacement of existing districts, resulting in new districts with different geographical boundaries. The basic purpose of decennial redistricting is to equalize population among electoral districts after publication of the United States census indicates an increase or decrease in or shift of population.
The Texas Constitution requires the legislature to redistrict Texas house and senate seats during its first regular session following publication of each United States decennial census (Section 28, Article III). After each census, State Board of Education seats also must be redistricted to bring them into compliance with the one-person, one-vote requirement.