D_3_Polygon Bangladesh Population Density Map
The same 165.5 million people, drawn with 8, 64, 600, 8,202 and 107,955 polygons. By division, half of Bangladesh lives on 44.9% of the land; village by village it is 13.5%. Behind the count: the 2022 census enumerated 106.8% of the households its quick count had listed, 2,753 villages have nobody living in them, and 12 city corporations hold 12.7% of the people on 0.96% of the land.
Write-up
The question
How does the picture of where Bangladesh's people live change as the same census is cut into smaller and smaller polygons — and what happened behind the count?
Methods
- BBS Population and Housing Census 2022 GIS layers (last update 21 May 2023): 8 divisions, 64 districts, 600 upazilas/thanas, 8,202 unions and city/municipal wards, 107,955 villages/mahallas, 12 city corporations and 328 municipalities, each with population, sex, household size, people abroad (NRB) and census household counts.
- Areas computed in WGS 84 / UTM zone 46N (EPSG:32646); density = people per km² of each polygon.
- The ladder: at each level, polygons are ranked from densest to emptiest and the share of land that holds half of the people is read off the cumulative curve — the modifiable areal unit problem in one number.
- Village check: villages were summed by union. In 81 unions (mostly city-corporation wards) several village polygons repeat the ward's population (3,403,360 people too many); there, villages were scaled to the union total, so the villages add up to exactly 165,498,422.
- Behind the count: households enumerated ÷ households in the pre-census quick count (BBS 'completion'), people abroad per 1,000 residents, and household size — mapped by union; unions with fewer than 200 households (forests, chars) are greyed out.
- Urban: city corporations and municipalities taken from their own BBS polygons; villages carry the BBS rural/urban (RMO) code.
- Maps and charts in Python (GeoPandas, Matplotlib). Web map: TopoJSON (simplified, quantized; 107,955 villages split into 600 upazila files of ~80 kB loaded on demand) in Leaflet on open basemaps.
Findings
Same people, five cuts: half of Bangladesh lives on 44.9% of the land by division, 30.7% by district, 24.1% by upazila, 18.6% by union and 13.5% by village.
The median village has 910 people on 0.76 km²; the densest village polygon, Geneva Camp in Dhaka, packs about 487,211 people per km².
2,753 village polygons have no residents — 6,397 km² (4.4% of the land): the Sundarbans, river chars, reserved forests and water.
12 city corporations hold 21,078,551 people (12.7%) on 0.96% of the land; 328 municipalities hold 17,913,989 more (10.8%). Dhaka South is the densest at 43,322 people per km².
Behind the count: enumerators interviewed 41,068,281 households, 106.8% of the 38,453,495 in the pre-census quick count — highest in Chattogram division (110.2%), lowest in Mymensingh (102.8%); 1,038 unions were above 120%.
5,077,160 Bangladeshis were counted as living abroad (30.7 per 1,000 residents): 61.5 per 1,000 in Chattogram and 52.0 in Sylhet, but 6.6 in Rangpur; Titas (Cumilla) tops the upazilas at 128.3.
Data note: summing the villages as published gives 168,901,782 people, 3,403,360 more than the union totals, because 81 city wards repeat their population on several village polygons.
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