I have a question:

State legislatures define the borders of their congressional districts when they “redistrict”, every ten years. The number of districts per state is assigned on the basis of the census (this is “apportionment”).

How are the borders of congressional districts defined?

Do state legislatures pass what amounts to a list of complex geographical shapes? Presumably, but what is the form that this takes? It could be a list of nine digit zip codes, or a shape made out of points defined precisely by latitude and longitude. Is the definition of the districts uniformly determined by the states, or set by the Committee on House Administration (with jurisdiction over House elections?). Are the districts determined by ad hoc metrics, varying by state?

Does anyone have the actual legislation handy that a state passed in defining their boundaries? That might be helpful to see.

I’m asking this because converting addresses to nine digit zip codes or to discrete points within a predefined shape file only really becomes reliable if this lines up with a discrete definition of what congressional districts actually are.

The Constitution Annotated has a bunch of information about getting House districts to represent approximately the same population size, but no information on how districting is defined in practice (that I could find.) If you want to double check, see page 109 of the section on the legislature, in the section starting:

SECTION2. Clause 1. The House of Representatives shall
be composed of Members chosen every second Year by the Peo-
ple of the several States, and the Electors in each State shall
have the Qualifications requisite for Electors of the most nu-
merous Branch of the State Legislature.

Anyone happen to know how districts are actually defined?