St. Louis Region
Jefferson County GIS maps are not boundary surveys
Jefferson County's assessor offers GIS and property-viewer tools, but the county says true property-line questions require a survey or recorded plat.
A parcel viewer is handy until the question turns into a boundary question.
Jefferson County GIS tools can help with a first pass on owner records, parcel IDs, roads, subdivision lot lines, taxing districts, and other map layers. They are good for getting oriented before you call an office or compare nearby parcels.
The hard limit is the property line itself. The county’s GIS materials direct true property-line questions to a survey or recorded plat, and warn that tax maps are not exact boundary proof.
That difference can save trouble before a fence, driveway, sale, neighbor dispute, or permit sketch. Use GIS to orient yourself. Use a recorded plat, survey, or qualified professional when the boundary has to be exact.
References
More from Jefferson County: browse every local note for the county.
Last checked against the sources above: July 16, 2026.