Calibrate parcel lines

Show where corners really are on the aerial photo, and the parcel lines follow. County map

County

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Correction

–Off by, before (RMS)

–Left over, after (RMS)

Add a point to see how far off the lines are.

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State parcel lines (original) Corrected parcel lines Points and arrows Aerial photo

Photo brightness

State parcel lines Corrected lines Where it really is (ground) Where the parcel lines put it

Points

Good to know

The photo is USDA NAIP aerial imagery: Montana’s 2025 flight at 30 cm (about a foot) per pixel by default, the 2023 flight at 60 cm, or the USGS 1 m map. Sharper photos make corners easier to see, but every NAIP photo is placed only to within about 5 m (16 ft), so points read off any photo are "rough" or "good". Comparing 2025 and 2023 at the same spot shows how much the photos themselves wander. A stake you stood on with GPS is "good"; only a licensed surveyor's fix is "surveyed", and it counts ten times as much. A fence shows where land is used, which is often not the true line. The state's parcel data is never changed: corrected lines are a separate layer, and only a licensed land surveyor establishes a boundary. Never move or dig at a survey stake, and only go on land with the owner's permission.

Imagery: USDA NAIP 2025 (30 cm), Montana State Library · Parcels: Montana Cadastral