One source, one geographic edition
We use the simplified India ADM2 GeoJSON linked by geoBoundaries metadata, pinned at repository commit 9469f09. The source represents 2021 and was built on 12 December 2023. The Bihar extraction has 38 features.
Names are joined through an explicit crosswalk. West Champaran maps to Pashchim Champaran, East Champaran to Purba Champaran, and Kaimur to Kaimur (Bhabua). Aurangabad has a namesake elsewhere in India, so its match is restricted to the documented Bihar coordinate envelope.
BU-01 through BU-38 are stable project identifiers assigned by the crosswalk. They are not Census or Local Government Directory codes. Source shape IDs are retained. No historical-boundary equivalence is assumed.
Mapped area
Turf area 7.4.0 calculates geodesic polygon area in square metres, accounting for polygon holes and multiple polygon parts. We divide by 1,000,000 for km². Values are calculated before rounding.
Ranking sorts the unrounded area values. The story ratio divides the largest calculated area by the smallest. Display labels normally round to the nearest km²; tables may show one decimal. These are approximate areas from simplified shapes, not official administrative measurements.
East–west bounding span
For each shape, take minimum and maximum longitude and latitude. At the midpoint latitude of that bounding box, Turf distance calculates the great-circle distance between the western and eastern meridians, in kilometres.
This is a geographic envelope measure. It is not the district’s road width, a journey length or the longest distance inside the polygon. The calculation can include space outside an irregular polygon.
A map is a particular view
The display uses a fixed equirectangular-style local projection: horizontal longitude scaling 155 SVG units per degree and vertical latitude scaling 172 units per degree. It is a small-region exploratory illustration, not a survey map. The north arrow indicates increasing latitude.
SVG coordinates are rounded to 0.1 display units for a smaller page. Calculations use the original retrieved geometry. The downloadable subset retains original source coordinates. Silhouettes outside the atlas are explicitly not to scale.
Comparisons and missing values
Both comparison selections use the same indicator, unit, source and reference period. Population, urban share and literacy refer to Census 2011; map area and envelope span refer to the 2021 geographic source. Bars start at zero and use one shared upper bound. Values are also supplied in a table.
No imputation is performed. Urban share is urban count divided by total count, multiplied by 100. The source’s 2011 density is preserved rather than recomputed with a later polygon area. Male/female population counts, workforce and religion remain unavailable.
Population projections
The 2026 population display uses UNFPA’s published district projections for 1 March 2026, not a new Census. The report applies a district ratio method with Government of India state projection inputs. Its 38 district totals sum to 132,265,997, while the state input is 132,265,000 because it is expressed in thousands. We preserve both source values and disclose the 997-person difference.
The annual model pace is ((2026 projection ÷ 2021 projection)^(1/5) − 1) × 100. Lakh displays are rounded; calculations use source integers. Other demographic rates remain dated 2011. The source’s sex-component totals do not reconcile cleanly, so only its total-population projections are used. Read the projection source and method.
The population correction
The Bihar DES district feed transposes the total, rural and urban population entries for East and West Champaran. We correct those three fields against official district records, retaining the original replies and the correction evidence. Other fields remain with the district named in the source.
All 38 district counts reconcile to 104,099,452 people: 92,341,436 rural and 11,758,016 urban. A state sum alone would not have revealed the Champaran swap. These are named-district counts for 2011; they have not been spatially redistributed onto the later map.
Income, crops and product entries
DES reports gross district domestic product for 2023–24 at current prices in lakh rupees. We divide by 100 to show crore. Per-capita income remains a separate rupee measure. Crop production refers to 2024–25; rice, wheat and maize are components of the cereals total. District totals reconcile with the state source. We exclude an ambiguous food-grain field and do not invent a seasonal split.
The product register preserves the labels in MoFPI’s March 2024 PMFME list. A designation is not a production rank, exclusive district identity or GI registration.
Two climate records
IMD rainfall normals describe 1951–2000 and the publication’s district geography as at January 2010. Annual normals stay as printed; the monsoon total sums June through September. Small differences between annual and summed monthly values reflect source rounding.
NASA POWER temperature data is sampled at one point on each source polygon, from a coarse MERRA-2 grid. We explicitly requested and checked 2001–2020. Summer means March–May; winter means December–February, with equal month weights. Model extrema are not observed station records or average daily highs and lows. These point samples are not spatial averages for entire districts.
A dated heritage register
The parliamentary district table from July 2023 totals 70 sites across 17 listed districts. Unlisted districts remain missing, not zero. The undated NMA list retains its original district labels, which can be historical.
A separate March 2026 source lists 71 sites without a district field. We show those names separately and do not assign modern districts from locality names. A listing does not establish opening hours or visitor access.
Validation and uncertainty
The build checks unique district and shape IDs, expected membership, coordinate ranges and closed rings, finite positive measurements, source references, units and periods. It recomputes geographic and seasonal calculations, checks state population and crop totals, and verifies source-file and photograph hashes.
Our checks do not certify official boundary status, shared-border topology or legal accuracy. Source metadata reports 736 national features while the downloaded simplified file has 735; the discrepancy is disclosed and unresolved. The Bihar crosswalk matches 38 unique shapes.
Original source updates are not ingested automatically. A later edition needs a deliberate review of names, source changes, geography, licences and calculations.