Geographic Boundary
The defined edges of an area being studied or regulated—often a zip code, census tract, county line, or a custom radius around a polluting facility.
Related terms
Census Tract A small statistical subdivision of a county (typically 1,200 to 8,000 people) used by the Census Bureau as a stable geographic unit for reporting demographic and health data. Proximity Buffer A mapped zone (often a 1-mile or 3-mile radius) drawn around a hazardous site to define the area of primary impact. Used by regulators to identify which homes and people are most at risk.