Coverage analysis
What 5 minutes covers in Columbia.
Three-river-bounded and military-base-clipped, Columbia isochrones radiate along the interstate spines in a starfish pattern from the I-20/I-26/I-77 hub, with the Congaree and Fort Jackson eliminating westward and eastern expansion respectively.
At 5 minutes, the Columbia isochrone captures the hyperlocal footprint — the area where customers make routine, repeat visits without deliberate trip planning. Unlike a 2–4 km² in a suburban grid; far less in a grid with barriers circle, the real road-network polygon follows Columbia'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 5 minutes: QSR, coffee, convenience, pharmacy, urgent care, car wash, gas station. The 5-minute isochrone is the standard input for footprint mapping and proximity-marketing radius decisions.
The city-level population of 136,632 and a median household income of $54,000 give a sense of Columbia'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.