Understanding St. Louis's geography
Why St. Louis's drive times defy radius math.
The Mississippi River creates a hard eastern boundary for Missouri-side sites — bridge crossings add 5-8 minutes during peak periods, meaning East St. Louis and Belleville, IL are functionally outside a 15-minute isochrone for many downtown locations. Clayton's Central West End and the I-64 corridor through Brentwood and Richmond Heights capture the highest-income daytime population in the metro.
The I-270 arc through Chesterfield and Ballwin in west St. Louis County is the metro's most active QSR belt, anchored by Chesterfield Mall and dense strip retail along Clarkson Road. Site selectors should weigh South County around Tesson Ferry Road, where the trade area population has grown faster than retail supply over the past decade.