Buying Land in St. Louis County, Missouri

Real County Zoning Exists, But It Only Covers Unincorporated Land -- Check Which Jurisdiction Applies First

Case-by-case / verify locally

St. Louis County's Department of Planning administers a genuine Zoning Ordinance (Chapter 1003) and Subdivision Ordinance (Chapter 1005) for unincorporated county land -- this is not one of the no-zoning rural counties covered elsewhere in this project. But St. Louis County also contains 88 separate incorporated municipalities (Clayton, Chesterfield, Florissant, Ballwin, and dozens more), each running its own zoning and building code independent of the county's. Before you evaluate a specific parcel's buildable use, minimum lot size, or setback rules, confirm whether it sits in unincorporated county territory or inside one of those 88 cities -- the answer determines which rulebook and which office applies.

Unincorporated Land With Real Acreage Is Scarce, But the 'NU' District Sets a 3-Acre Floor Where It Exists

Case-by-case / verify locally

The unincorporated county's Non-Urban ("NU") zoning district generally prohibits creating a new lot smaller than 3 acres (with narrow carve-outs for uses like fire stations or utility facilities), making it the closest thing to acreage-buyer-relevant zoning in a county this dense and suburbanized. Genuinely rural-feeling unincorporated land is a small and shrinking share of the county's roughly 500 square miles, concentrated mostly toward the western and southwestern edges near the Meramec River corridor -- most of what's listed as "land" here is really a small residential or infill lot inside city limits.

Nearly All of the County Is Sewered -- Septic Is the Exception, Not the Rule

Generally favorable

The Metropolitan St. Louis Sewer District (MSD) serves all of St. Louis City plus roughly 90% of St. Louis County, having annexed most of the remaining unincorporated area back in 1977. For the large majority of parcels here, wastewater means an MSD sewer connection, not a septic permit -- a meaningfully different (and typically simpler) picture than the septic-heavy rural counties covered elsewhere in this project. The remaining sliver of unsewered land would route through the county health department for an individual sewage disposal system permit instead.