California Population Density II

100%

California Population Density II

✓ Published0🌍 Public

Last edited Nov 13, 2016

Created on Nov 13, 2016

A choropleth map of California displays population density per square mile across 23,198 block groups, using a sequential red color scale and a square-root axis legend. Drawn with `d3.geoPath` and SVG, the visualization loads topology from a preprocessed `topo.json` file, created by scripts that download Census block group boundaries and ACS population data via the Census API. The `prepublish` script projects, joins, and simplifies the data using `geo2topo`, `topomerge`, and `topoquantize`. County borders are overlaid as semi-transparent outlines.

AI-generated description

A variation of my California population density map using California’s 23,198 block groups rather than its 8,043 tracts. The example exhibits how useful the Census API is: the prepublish script here can automatically grabs the list of counties for the desired state and then the population data for each block group.

gpl-3.0 Licensed

Similar vizzes

Loading thumbnail…

California Population Density

This choropleth map of California visualizes population density per square mile at the census tract level, using a sequential color scale to encode density intervals. The map renders as SVG, with tract boundaries colored via a threshold scale and county outlines overlaid. The visualization relies on D3 v4’s `d3.geoPath`, `d3.scaleThreshold`, and `d3.scaleSqrt`, and uses `topojson` to handle the TopoJSON data. Population data comes from the 2014 American Community Survey 5-Year Estimate, joined with Census Bureau shapefiles.

MMTClass

92% match

Loading thumbnail…

California Population Density

This map visualizes population density across California census tracts, coloring each tract according to its population per square mile. It uses a threshold color scale (d3.scaleThreshold) with a sequential color scheme, and renders the state's county boundaries as an overlay. The visualization is built with d3.geoPath for map projections and topojson for handling the topology data. The underlying data comes from the American Community Survey’s 2014 5-year estimates, joined with Census Bureau tract shapefiles and processed through the command-line tools geo2topo, toposimplify, and topomerge to compute densities and simplify the geometry.

Mmbostock

87% match

Loading thumbnail…

Untitled

This choropleth map shows population density per square mile across California counties, using a sequential orange-red color scale with a threshold legend. The visualization loads GeoJSON topology data and renders county boundaries as SVG paths via `d3.geoPath`. Colors are assigned by county ID using `d3.schemeOrRd[9]`, while the legend uses `d3.scaleThreshold` and `d3.axisBottom` to display the value ranges. County outlines are drawn from a separate topology object with a semi-transparent black stroke.

AAlice Hua

87% match

Loading thumbnail…

Merged Choropleth

This choropleth map visualizes population density across California census tracts, using the 2014 American Community Survey 5-Year Estimate. The map merges adjacent tracts with similar density into single polygons, reducing the file size from 1.5M to 328K and improving rendering speed and visual clarity. The d3.geoPath renders the projected shapes, while d3.scaleThreshold and d3.schemeOrRd assign colors, and d3.scaleSqrt positions the legend. The code uses topomerge and toposimplify from the topojson library to consolidate boundaries, with county borders overlaid as an outline.

Mmbostock

85% match

Loading thumbnail…

geo2svg

A static choropleth map of California population density by census block group, colored with the OrRd sequential scheme. The map, generated from the command line using the geo2svg tool from d3-geo-projection, visualizes density classes derived from ACS 5-year estimates joined to Census block group boundaries. The workflow projects shapefiles via `geoproject`, simplifies topology with `toposimplify`, and renders SVG paths with `geo2svg`, adding county boundary strokes and a legend.

Mmbostock

83% match

Loading thumbnail…

Population Choropleth

A population choropleth of U.S. counties uses a logarithmic color scale to show population density, ranging from pale yellow to dark blue. The map projects counties with d3.geo.albersUsa() and renders them as SVG paths via d3.geo.path. Density is calculated by dividing each county’s population (from the 2010 Census shapefile, converted to TopoJSON) by its projected area, with the color domain set between the 1st and 99th percentiles. The topojson.feature API extracts county geometries for display.

Mmbostock

78% match

Loading thumbnail…

Untitled

A choropleth map of population density by census block group uses a sequential color scale from the d3-scale-chromatic library to shade geographic regions. The visualization renders as SVG via d3.geoPath, with a threshold scale mapping density values to the OrRd color scheme and a legend using d3.axisBottom. It loads TopoJSON data containing block group polygons, fills each path according to its population per square mile, and outlines counties with a subtle stroke. The code applies d3.scaleThreshold and d3.scaleSqrt to encode the data range.

JJohan van Beusekom

78% match

Loading thumbnail…

Untitled

This visualization displays population density per square mile across U.S. census block groups using a choropleth map. A threshold color scale with d3.schemeOrRd maps density values to sequential red tones, while a legend with a sqrt scale and axis shows the breakpoints. The code loads TopoJSON data via d3.json, renders block group polygons with d3.geoPath, and overlays county boundaries as black outlines. An interactive legend is constructed with rect elements and d3.axisBottom.

CCurran Kelleher

77% match