Where our lot lines come from

What the coverage tiers actually mean

Parcel boundaries in the United States are not published by one authority. Each county assessor digitizes its own tax maps, and a state may or may not aggregate those files into a single statewide service. Where a state runs a modern aggregated service, we can draw a lot line for nearly any address in it. Where it does not, coverage is county-by-county, and rural counties are the ones most likely to be missing.

That is the only thing the tiers describe: how much of the state we can reach from free public services, not how accurate the resulting line is. A statewide service can still carry parcels digitized decades ago from paper maps.

How accurate is a public parcel line?

County GIS parcels are assessment tools. They exist so a county can tax the right piece of land, and they are typically drawn by fitting deed calls onto an aerial photograph. The result is usually within a few feet of the surveyed line, and sometimes further off than that. Enough to matter when you are siting a fence, a pool or an addition against a setback or an easement edge. Only a boundary survey by a licensed surveyor establishes where your line legally sits.

We show the drift rather than hiding it. When the public parcel geometry disagrees with the geocoded address, the report says so, and the ground control point tool lets you pull the boundary onto features you can identify in the aerial image.

Easements are a separate question

Very few counties publish an easement layer at all. Even in the states shaded strongest above, an easement is normally found in the recorded document chain, not in GIS. Which is why the audit reads your title commitment and why every state page links to the office that holds the recorded instruments.

If you want the records route, how to find your easement document walks through it, and easement law by state covers what your state requires.