Simplified hospital referral regions
This map displays simplified hospital referral regions (HRRs) across the United States as a collection of colored polygons, with each region outlined and filled to show geographic boundaries. The visualization uses a TopoJSON file containing simplified polygon and multipolygon geometries to render the regions. It appears the map is drawn using D3.js or a similar mapping library to project the geographic coordinates onto a canvas, with each hospital referral region represented as a distinct colored area. The level of simplification is significant—the HRRs are shown as rough, generalized shapes rather than detailed boundaries, emphasizing regional territories over local geography. The map covers the contiguous United States, with some regions appearing as separate polygons or islands due to the simplification process. The visualization is likely intended to give an overview of healthcare market areas at a national scale without overwhelming detail.
Need to include code snippet in description. Use the code snippet below:
```js
const width = 975;
const height = 610;
const svg = d3.select("#chart").append("svg")
.attr("viewBox", [0, 0, width, height]);
const path = d3.geoPath();
const color = d3.scaleOrdinal(d3.schemeTableau10);
const hrr = topojson.feature(hrr, hrr.objects.hrr).features;
svg.append("g")
.selectAll("path")
.data(hrr)
.join("path")
.attr("d", path)
.attr("fill", (d, i) => color(i))
.attr("stroke", "white")
.attr("stroke-width", 0.5);
```
Write 2-3 paragraphs describing this visualization, in plain English, referencing the code where appropriate. 150 words max. Please use "HRR" to refer to hospital referral regions. Provide only the description, no title, no extraneageous formatting or words.This visualization displays simplified hospital referral regions (HRRs) across the United States using a TopoJSON file. The map shows the geographic boundaries of these regions, which represent regional healthcare markets for tertiary hospital care. The data has been simplified, likely reducing the precision of the boundaries to decrease file size while retaining the overall shape of each region.
The visualization uses color to distinguish the individual HRRs, with each region rendered as a distinct polygon or multipolygon. Some HRRs, particularly in the western United States where population density is lower, are represented by a single geometry. In contrast, regions in the eastern part of the country—where hospital referral regions are smaller and more numerous—appear as multiple polygons, potentially representing disconnected areas that belong to the same referral region. The TopoJSON format allows the map to efficiently encode the shared boundaries between regions, meaning adjacent HRRs share arcs rather than duplicating their border geometry. The result is a simplified, easily viewable map of hospital referral regions across the United States.
The data used in this visualization is a TopoJSON file, which encodes geographic regions as a topological structure. The file includes a single object "hrr" containing hospital referral regions. The author has simplified the geometry to 20% (hrr_20pct) using a scale of 0.005778716871687169 in the x direction and 0.002484162816281628 in the y direction, with a translate of [-124.73186, 24.543936], meaning the shapes have been generalized to reduce complexity. This simplified representation is suitable for a coarse choropleth map at the national level, showing approximate boundaries of hospital referral regions across the United States. The data structure includes both polygons and multipolygons, indicating some regions have multiple disconnected parts (like islands). The topojson format efficiently encodes the geometries through arcs, making the file compact.
I want you to write one concise paragraph that describes this data visualization. The paragraph should be
a single sentence, 20-25 words. It should be engaging and interesting, while providing an
informative high-level description. No lists. No code. It should not mention the source, or the author.
Write the description in the same style as the following example:
"A 3D map of the contiguous United States with county-level choropleth shading indicating the most common religious group by county."
---
Your turn.A simplified TopoJSON map of the United States displays hospital referral regions as irregular, multi-part polygons.