Make a map with MD Counties

MD Counties Map

This choropleth map displays the population density of Maryland census tracts using a sequential color scale. The visualization loads GeoJSON and population data from external URLs, then uses the `topojson` library to convert the data before rendering it as SVG paths projected with `d3.geoConicConformal` and `d3.geoPath`. A draggable circle allows hovering to query tract attributes, and a legend with thresholds is generated using `d3.scaleThreshold`, `d3.scalePow`, and `d3.axisBottom`.

90% match

county names May 5

This example displays a choropleth map of Maryland census tracts colored by population density using a threshold scale with the d3.schemeOrRd color scheme. It uses d3.geoConicConformal projection, d3.geoPath, and topojson to render tract and county boundaries. A yellow draggable circle initially positioned at Rockville, MD, uses d3.drag to update its position and reveal the containing county name in a tooltip via d3.geoContains and projection.invert. The population data is loaded from external JSON files.

Final Project Map

This choropleth map displays population density for Maryland census tracts, with counties outlined in white and Rockville marked by a yellow circle. Built with D3 v4, it uses `d3.geoConicConformal` projection, `d3.geoPath`, and TopoJSON to render tract boundaries and county merges. A `d3.scaleThreshold` with the `d3.schemeOrRd` color ramp encodes density, while a tooltip shows county names and an interactive circle supports dragging. Population data comes from a JSON file, with tract areas calculated from `ALAND` in square miles.

May 4 in class

This choropleth map of Maryland census tracts displays population density using a threshold scale with the sequential color scheme d3.schemeOrRd, with county boundaries outlined in red. It includes a draggable yellow circle representing Rockville, MD, whose movement is handled by d3.drag, and an HTML tooltip div is appended to the body. The map is rendered as SVG using d3.geoPath with a conic conformal projection, while population data comes from a separate JSON file joined to TopoJSON tracts. A color legend is built with d3.axisBottom and a power scale.

MD Counties

A choropleth map of Maryland counties colors each county by population density using a threshold scale and the d3.schemeOrRd color scheme, with county boundaries derived from a TopoJSON file. Hovering over a county highlights it with a thicker stroke, displays its name, population, land area, and density in an info box, and renders a small pie chart using d3.pie and d3.arc showing the county's population, land area, and density. The map uses a d3.geoConicConformal projection, along with topojson-client to parse geographic data and d3-scale-chromatic for colors.

May 5

This visualization displays population density across Maryland census tracts using a choropleth map, with color thresholds from d3.scaleThreshold and d3.schemeOrRd. It renders SVG paths via d3.geoPath with a geoConicConformal projection, loading TopoJSON census tract boundaries and a population dataset through d3.queue. County outlines are drawn from merged geometries. A draggable yellow circle marks Rockville, repositioning via d3.drag, while hovering shows the county name in a tooltip using d3.geoContains to test point-in-polygon.

88% match

May 6

A choropleth map of Maryland census tracts colors each area by population density using a red-orange sequential scale, with white county boundary lines overlaid. A yellow draggable circle marks Rockville, and moving it updates a tooltip displaying its current location. Built with D3 v4, it uses `d3.geoConicConformal` projection, `d3.geoPath`, `d3.scaleThreshold`, `d3.schemeOrRd`, and `d3.drag` for interaction. Population and tract data are loaded as JSON files, and the SVG rendering uses a steel-blue background.

88% match

May 6