Coverage analysis
What 30 minutes covers in Detroit.
Detroit River creates a hard international southern wall, pushing all suburban isochrone growth north along Woodward, I-75, and I-94 spokes into Oakland and Macomb counties.
At 30 minutes, the Detroit isochrone captures the regional catchment — a zone where trips are planned but customers are willing to cross neighborhood boundaries. Unlike a 100–350 km² circle, the real road-network polygon follows Detroit's actual highway corridors, accounts for bridge and interchange chokepoints, and respects the natural and built barriers that force drivers to detour.
Best-fit categories at 30 minutes: Big-box, regional dining, car dealership, furniture, healthcare anchor, sporting goods. The 30-minute isochrone is the standard input for cannibalization studies and multi-unit expansion modeling.
The city-level population of 639,000 and a median household income of $34,000 give a sense of Detroit's economic density, but the figure that matters for site selection is the population inside the polygon — not the city as a whole. That number shifts dramatically depending on whether you're drawing from a high-density urban core or a lower-density suburban corridor. Use the tool above to set your actual candidate location, then generate the isochrone to see the real catchment.