Lines, 2026 edition -- Call the Map (callthemap.com/lines)

Ten alternative congressional maps for all 50 states, 435 districts on
the 2020 apportionment, each drawn by a computer toward one goal: Republican
and Democratic gerrymanders in two versions (durable: every seat drawn for
the party holds through a 10-point national loss; aggressive: the most
seats the arithmetic allows, by thin margins, ignoring the Voting Rights
Act and the courts); a proportional map and a competitive one, both within
ordinary shapes; and four maps drawn from geography alone (shortest straight lines; town and country, each district as
alike in density as possible; slices, each district the same mix of city and
country; fewest county splits).
They are hypothetical maps, not proposals and not a forecast.

Every district is built from whole 2020 Census voting districts (VTDs; block
groups in CA, HI, OR and WV; county subdivisions in parts of Maine), is
contiguous, and is within 1% of its state's ideal population (DEV_PCT gives
the exact deviation). Enacted maps are balanced to the person by splitting
census blocks, which a whole-precinct map cannot do: to adopt one of these
maps, rebalance it at block level first.

FILES
  atlas-2026-<map>.zip           one map's district polygons as a shapefile
                                 (.shp/.shx/.dbf/.prj/.cpg), NAD83
                                 longitude/latitude, simplified to about 250 m
                                 and clipped to the shoreline (Census 2025
                                 cartographic boundaries)
  atlas-2026-vtd-assignments.zip every map, exactly: one row per 2020 VTD
                                 (GEOID20, STATE) and one column per map giving
                                 its district -- the file redistricting tools
                                 import (Dave's Redistricting, Districtr and
                                 others accept VTD assignment files)
  atlas-2026-districts.csv       every drawn district's numbers, all maps
A single state's map as GeoJSON is one click on its close-up at
callthemap.com/lines; `ogr2ogr -f GeoJSON out.geojson <map>.shp` converts a
whole map.

FIELDS
  STATE, STATEFP, DISTRICT, MAP
  POP20        2020 Census population
  DEV_PCT      deviation from the state's ideal district population, %
  VAP20        2020 voting-age population
  WHITE_PCT, HISP_PCT, BLACK_PCT, ASIAN_PCT, OTHER_PCT
               share of voting-age population: non-Hispanic white alone,
               Hispanic, non-Hispanic Black alone, non-Hispanic Asian alone,
               everyone else (non-Hispanic)
  MARGIN24     2024 presidential margin, Democrat minus Republican, points
  DWIN_PCT     chance a Democrat wins in a year when the national popular
               vote is even (the Atlas's default), from the 2024 margin with
               the curve fitted to Call the Map's House forecast (atlas.json
               "calibration"); an average relationship, not a race forecast

SOURCES
  Dave's Redistricting, VTD data (github.com/dra2020/vtd_data): 2020 Census
  shapes, population and voting-age population; precinct election returns
  from the Voting and Election Science Team (CC BY 4.0) and the
  Redistricting Data Hub. Where 2024 precinct returns are not in that
  package (AR, CT, ID, ME, MI, NJ, OK, OR, PA and the at-large AK, ND, SD),
  2020 precinct returns are carried forward by each county's actual
  2020-to-2024 swing.
  Method and code: scripts/atlas/ in the Call the Map repository.
