This example visualizes the spatial relationships between metropolitan statistical areas and their constituent counties, townships, and other administrative geometries. The code first builds a combined geometry table using SQL, merging overlapping regions across multiple spatial layers while excluding special cases like Boston. It then renders these shapes using D3.js, likely leveraging `d3.geoPath` for projection and canvas or SVG drawing. The query explicitly handles hierarchical and overlapping geographies, prioritizing township-level detail where available and falling back to county unions for other areas. The final visualization shows how different government boundaries interlock within U.S. metropolitan regions, with the SQL preprocessing ensuring no duplicated or missing polygons.