State legislatures are responsible for delimitation, though some legislatures delegate the authority to a multi-party or judicial commission. In all cases, new boundaries take the form of a bill, which governors must sign into law. Federal boundary delimitation conventionally follows the census every 10 years, but some states in recent years have redrawn boundaries at other times, for partisan advantage, known as gerrymandering, or to correct for changes in population.

Federal law dictates some of the criteria authorities use when delimiting legislative boundaries. These include population equity, boundary contiguousness, and racial and ethnic minority representation. The latter is the most controversial, requiring that districts be drawn specifically to ensure descriptive minority representation.  

Jurisdictions may apply other criteria. Usually they specify a hierarchy of criteria since some may be in conflict. These criteria include compactness (minimizing the distance between the farthest apart points in a district), respect for political subdivisions like municipalities and counties, and respect for communities of interest.

States using independent, multi-party or judicial commissions have had mixed results. On one hand, “independent redistricting” has enhanced public confidence. On the other, it has not relieved tensions among conflicting boundary delimitation criteria, and has not made elections more competitive overall.

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